Nucleoside derivatives as inhibitors of RNA-dependent RNA viral polymerase

ABSTRACT

The present invention provides nucleoside derivatives which are inhibitors of RNA-dependent RNA viral polymerase. These compounds are inhibitors of RNA-dependent RNA viral replication and are useful for the treatment of RNA-dependent RNA viral infection. They are particularly useful as inhibitors of hepatitis C virus (HCV) NS5B polymerase, as inhibitors of HCV replication, and/or for the treatment of hepatitis C infection. The invention also describes pharmaceutical compositions containing such nucleoside derivatives alone or in combination with other agents active against RNA-dependent RNA viral infection, in particular HCV infection. Also disclosed are methods of inhibiting RNA-dependent RNA polymerase, inhibiting RNA-dependent RNA viral replication, and/or treating RNA-dependent RNA viral infection with the nucleoside derivatives of the present invention.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is the National Stage of International Application No.PCT/US2002/01531, filed 9 Jul. 2003, which claims the benefit under 35U.S.C. 119(e) of U.S. provisional application No. 60/344,528, filed onOct. 25, 2001; provisional application No. 60/299,320, filed on Jun. 19,2001; provisional application No. 60/282,069, filed on Apr. 6, 2001; andprovisional application No. 60/263,313, filed on Jan. 22, 2001; thecontents of each of which are hereby incorporated by reference.

FIELD OF THE INVENTION

The present invention provides nucleoside derivatives which areinhibitors of RNA-dependent RNA viral polymerase. These compounds areinhibitors of RNA-dependent RNA viral replication and are useful for thetreatment of RNA-dependent RNA viral infection. They are particularlyuseful as inhibitors of hepatitis C virus (HCV) NS5B polymerase, asinhibitors of HCV replication, and for the treatment of hepatitis Cinfection.

BACKGROUND OF THE INVENTION

Hepatitis C virus (HCV) infection is a major health problem that leadsto chronic liver disease, such as cirrhosis and hepatocellularcarcinoma, in a substantial number of infected individuals, estimated tobe 2-15% of the world's population. There are an estimated 4.5 millioninfected people in the United States alone, according to the U.S. Centerfor Disease Control. According to the World Health Organization, thereare more than 200 million infected individuals worldwide, with at least3 to 4 million people being infected each year. Once infected, about 20%of people clear the virus, but the rest harbor HCV the rest of theirlives. Ten to twenty percent of chronically infected individualseventually develop liver-destroying cirrhosis or cancer. The viraldisease is transmitted parenterally by contaminated blood and bloodproducts, contaminated needles, or sexually and vertically from infectedmothers or carrier mothers to their off-spring. Current treatments forHCV infection, which are restricted to immunotherapy with recombinantinterferon-α alone or in combination with the nucleoside analogribavirin, are of limited clinical benefit. Moreover, there is noestablished vaccine for HCV. Consequently, there is an urgent need forimproved therapeutic agents that effectively combat chronic HCVinfection. The state of the art in the treatment of HCV infection hasbeen reviewed, and reference is made to the following publications: B.Dymock, et al., “Novel approaches to the treatment of hepatitis C virusinfection,” Antiviral Chemistry & Chemotherap. 11: 79-96 (2000); H.Rosen, et al., “Hepatitis C virus: current understanding and prospectsfor future therapies,” Molecular Medicine Today, 5: 393-399 (1999); D.Moradpour, et al., “Current and evolving therapies for hepatitis C,”European J. Gastroenterol. Hepatol., 11: 1189-1202 (1999); R.Bartenschlager, “Candidate Targets for Hepatitis C Virus-SpecificAntiviral Therapy,” Intervirology, 40: 378-393 (1997); G. M. Lauer andB. D. Walker, “Hepatitis C Virus Infection,” N. Engl. J. Med., 345:41-52 (2001); B. W. Dymock, “Emerging therapies for hepatitis C virusinfection,” Emerging Drugs, 6: 13-42 (2001); and C. Crabb, “Hard-WonAdvances Spark Excitement about Hepatitis C,” Science: 506-507 (2001);the contents of all of which are incorporated by reference herein intheir entirety.

Different approaches to HCV therapy have been taken, which include theinhibition of viral serine proteinase (NS3 protease), helicase, andRNA-dependent RNA polymerase (NS5B), and the development of a vaccine.

The HCV virion is an enveloped positive-strand RNA virus with a singleoligoribonucleotide genomic sequence of about 9600 bases which encodes apolyprotein of about 3,010 amino acids. The protein products of the HCVgene consist of the structural proteins C, E1, and E2, and thenon-structural proteins NS2, NS3, NS4A and NS4B, and NS5A and NS5SB. Thenonstructural (NS) proteins are believed to provide the catalyticmachinery for viral replication. The NS3 protease releases NS5B, theRNA-dependent RNA polymerase from the polyprotein chain. HCV NS5Bpolymerase is required for the synthesis of a double-stranded RNA from asingle-stranded viral RNA that serves as a template in the replicationcycle of HCV. NS5B polymerase is therefore considered to be an essentialcomponent in the HCV replication complex [see K. Ishi, et al.,“Expression of Hepatitis C Virus NS5B Protein: Characterization of ItsRNA Polymerase Activity and RNA Binding,” Hepatology, 29: 1227-1235(1999) and V. Lohmann, et al., “Biochemical and Kinetic Analyses of NS5BRNA-Dependent RNA Polymerase of the Hepatitis C Virus,” Virology, 249:108-118 (1998)]. Inhibition of HCV NS5B polymerase prevents formation ofthe double-stranded HCV RNA and therefore constitutes an attractiveapproach to the development of HCV-specific antiviral therapies.

It has now been found that nucleoside compounds of the present inventionand certain derivatives thereof are potent inhibitors of RNA-dependentRNA viral replication and in particular HCV replication. The5′-triphosphate derivatives of the nucleoside compounds are inhibitorsof RNA-dependent RNA viral polymerase and in particular HCV NS5Bpolymerase. The instant nucleoside compounds and derivatives thereof areuseful to treat RNA-dependent RNA viral infection and in particular HCVinfection.

It is therefore an object of the present invention to provide nucleosidecompounds and certain derivatives thereof which are useful as inhibitorsof RNA-dependent RNA viral polymerase and in particular as inhibitors ofHCV NS5B polymerase.

It is another object of the present invention to provide nucleosidederivatives which are useful as inhibitors of the replication of anRNA-dependent RNA virus and in particular as inhibitors of thereplication of hepatitis C virus.

It is another object of the present invention to provide nucleosidecompounds and certain derivatives which are useful in the treatment ofRNA-dependent RNA viral infection and in particular in the treatment ofHCV infection.

It is another object of the present invention to provide pharmaceuticalcompositions comprising the novel compounds of the present invention inassociation with a pharmaceutically acceptable carrier.

It is another object of the present invention to provide pharmaceuticalcompositions comprising the nucleoside compounds and derivatives thereoffor use as inhibitors of RNA-dependent RNA viral polymerase and inparticular as inhibitors of HCV NS5B polymerase.

It is another object of the present invention to provide pharmaceuticalcompositions comprising the nucleoside compounds and derivatives thereoffor use as inhibitors of RNA-dependent RNA viral replication and inparticular as inhibitors of HCV replication.

It is another object of the present invention to provide pharmaceuticalcompositions comprising the nucleoside compounds and derivatives thereoffor use in the treatment of RNA-dependent RNA viral infection and inparticular in the treatment of HCV infection.

It is another object of the present invention to provide pharmaceuticalcompositions comprising the nucleoside compounds and derivatives thereofin combination with other agents active against an RNA-dependent RNAvirus and in particular against HCV.

It is another object of the present invention to provide methods for theinhibition of RNA-dependent RNA viral polymerase and in particular forthe inhibition of HCV NS5B polymerase.

It is another object of the present invention to provide methods for theinhibition of RNA-dependent RNA viral replication and in particular forthe inhibition of HCV replication.

It is another object of the present invention to provide methods for thetreatment of RNA-dependent RNA viral infection and in particular for thetreatment of HCV infection.

It is another object of the present invention to provide methods for thetreatment of RNA-dependent RNA viral infection in combination with otheragents active against RNA-dependent RNA virus and in particular for thetreatment of HCV infection in combination with other agents activeagainst HCV.

It is another object of the present invention to provide nucleosidecompounds and certain derivatives thereof and their pharmaceuticalcompositions for use as a medicament for the inhibition of RNA-dependentRNA viral replication and/or the treatment of RNA-dependent RNA viralinfection and in particular for the inhibition of HCV replication and/orthe treatment of HCV infection.

It is another object of the present invention to provide for the use ofthe nucleoside compounds and certain derivatives thereof of the presentinvention and their pharmaceutical compositions for the manufacture of amedicament for the inhibition of RNA-dependent RNA viral replicationand/or the treatment of RNA-dependent RNA viral infection and inparticular for the inhibition of HCV replication and/or the treatment ofHCV infection.

These and other objects will become readily apparent from the detaileddescription which follows.

SUMMARY OF THE INVENTION

The present invention provides a method for inhibiting RNA-dependent RNAviral polymerase, a method for inhibiting RNA-dependent RNA viralreplication, and/or a method for treating RNA-dependent viral infectionin a mammal in need thereof, comprising administering to the mammal atherapeutically effective amount of a compound of structural formula Iwhich is of the stereochemical configuration:

or a pharmaceutically acceptable salt thereof;wherein B is selected from the group consisting of

-   A, G, and L are each independently CH or N;-   D is N, CH, C—CN, C—NO₂, C—C₁₋₁₃ alkyl, C—NHCONH₂, C—CONR¹¹R¹¹,    C—CSNR¹¹R¹¹, C—COOR¹¹, C—C(═NH)NH₂, C-hydroxy, C—C₁₋₃ alkoxy,    C-amino, C—C₁₋₄ alkylamino, C-di(C₁₋₄ alkyl)amino, C-halogen,    C-(1,3-oxazol-2-yl), C-(1,3-thiazol-2-yl), or C-(imidazol-2-yl);    wherein alkyl is unsubstituted or substituted with one to three    groups independently selected from halogen, amino, hydroxy, carboxy,    and C₁₋₃ alkoxy;-   E is N or CR⁵;-   W is O or S;-   Y is H, C₁₋₁₀ alkylcarbonyl, P₃O₉H₄, P₂O₆H₃, or P(O)R⁹R¹⁰;-   R¹ is hydrogen, C₂₋₄ alkenyl, C₂₋₄ alkynyl, or C₁₋₄ alkyl optionally    substituted with amino, hydroxy, or 1 to 3 fluorine atoms and one of    R² and R³ is hydroxy or C₁₋₄ alkoxy and the other of R² and R³ is    selected from the group consisting of    -   hydrogen,    -   hydroxy,    -   halogen,    -   C₁₋₄ alkyl, optionally substituted with 1 to 3 fluorine atoms,    -   C₁₋₁₀ alkoxy, optionally substituted with C₁₋₃ alkoxy or 1 to 3        fluorine atoms,    -   C₂₋₆ alkenyloxy,    -   C₁₋₄ alkylthio,    -   C₁₋₈ alkylcarbonyloxy,    -   aryloxycarbonyl,    -   azido,    -   amino,    -   C₁₋₄ alkylamino, and    -   di(C₁₋₄ alkyl)amino; or-   R² is hydrogen, C₂₋₄ alkenyl, C₂₋₄ alkynyl, or C₁₋₄ alkyl optionally    substituted with amino, hydroxy, or 1 to 3 fluorine atoms and one of    R¹ and R³ is hydroxy or C₁₋₄ alkoxy and the other of R¹ and R³ is    selected from the group consisting of    -   hydrogen,    -   hydroxy,    -   halogen,    -   C₁₋₄ alkyl, optionally substituted with 1 to 3 fluorine atoms,    -   C₁₋₁₀ alkoxy, optionally substituted with hydroxy, C₁₋₃ alkoxy,        carboxy, or 1 to 3 fluorine atoms,    -   C₂₋₆ alkenyloxy,    -   C₁₋₄ alkylthio,    -   C₁₋₈ alkylcarbonyloxy,    -   aryloxycarbonyl,    -   azido,    -   amino,    -   C₁₋₄ alkylamino, and    -   di(C₁₋₄ alkyl)amino; or-   R¹ and R² together with the carbon atom to which they are attached    form a 3- to 6-membered saturated monocyclic ring system optionally    containing a heteroatom selected from O, S, and NC₀₋₄ alkyl;-   R⁴ and R⁶ are each independently H, OH, SH, NH₂, C₁₋₄ alkylamino,    di(C₁₋₄ alkyl)amino, C₃₋₆ cycloalkylamino, halogen, C₁₋₄ alkyl, C₁₋₄    alkoxy, or CF₃;-   R⁵ is H, C₁₋₆ alkyl, C₂₋₆ alkenyl, C₂₋₆ alkynyl, C₁₋₄ alkylamino,    CF₃, or halogen;-   R¹⁴ is H, CF₃, C₁₋₄ alkyl, amino, C₁₋₄ alkylamino, C₃₋₆    cycloalkylamino, or di(C₁₋₄ alkyl)amino;-   R⁷ is hydrogen, amino, C₁₋₄ alkylamino, C₃₋₆ cycloalkylamino, or    di(C₁₋₄ alkyl)amino;-   each R¹¹ is independently H or C₁₋₆ alkyl;-   R⁸ is H, halogen, CN, carboxy, C₁₋₄ alkyloxycarbonyl, N₃, amino,    C₁₋₄ alkylamino, di(C₁₋₄ alkyl)amino, hydroxy, C₁₋₆ alkoxy, C₁₋₆    alkylthio, C₁₋₆ alkylsulfonyl, or (C₁₋₄ alkyl)₀₋₂ aminomethyl;-   R¹² and R¹³ are each independently hydrogen, methyl, hydroxymethyl,    or fluoromethyl; and-   R⁹ and R¹⁰ are each independently hydroxy, OCH₂CH₂SC(═O)C₁₋₄ alkyl,    OCH₂O(C═O)OC₁₋₄ alkyl, NHCEMeCO₂Me, OCH(C₁₋₄ alkyl)O(C═O)C₁₋₄ alkyl,    with the provisos that (a) when R¹ is hydrogen, one of R³ and R⁴ is    hydrogen, and R² is fluoro, then the other of R³ and R⁴ is not    hydrogen, halogen, azido, trifluoromethyl, C₁₋₄ alkyl, amino, C₁₋₄    alkylamino, di(C₁₋₄ alkyl)amino, or C₁₋₁₀ alkoxy; (b) when R¹ is    hydrogen, one of R³ and R⁴ is hydrogen, and R² is halogen, hydroxy,    C₁₋₆ alkoxy, or C₂₋₆ alkenyloxy, then the other of R³ and R⁴ is not    hydrogen, fluoro, or azido; and (c) when R¹ and R³ are hydrogen and    R² is hydroxy, then R⁴ is not hydroxy.

The present invention also provides novel compounds of structuralformula IV of the indicated stereochemical configuration which areuseful as inhibitors of RNA-dependent RNA viral polymerase. Thecompounds of formula IV are also inhibitors of RNA-dependent RNA viralreplication and are useful for the treatment of RNA-dependent RNA viralinfection:

wherein B is selected from the group consisting of

-   A, G, and L are each independently CH or N;-   D is N, CH, C—CN, C—NO₂, C—C₁₋₃ alkyl, C—NHCONH₂, C—CONR¹¹R¹¹,    C—CSNR¹¹R¹¹, C—COOR¹¹, C—C(═NH)NH₂, C-hydroxy, C—C₁₋₃ alkoxy,    C-amino, C—C₁₋₄ alkylamino, C-di(C₁₋₄ alkyl)amino, C-halogen,    C-(1,3-oxazol-2-yl), C-(1,3-thiazol-2-yl), or C-(imidazol 2-yl);    wherein alkyl is unsubstituted or substituted with one to three    groups independently selected from halogen, amino, hydroxy, carboxy,    and C₁₋₃ alkoxy;-   E is N or CR⁵;-   W is O or S;-   R¹ is hydrogen, C₂₋₄ alkenyl, C₂₋₄-alkynyl, or C₁₋₄ alkyl optionally    substituted with amino, hydroxy, or 1 to 3 fluorine atoms and one of    R² and R³ is hydroxy or C₁₋₄ alkoxy and the other of R² and R³ is    selected from the group consisting of    -   hydrogen,    -   hydroxy,    -   halogen,    -   C₁₋₄ alkyl, optionally substituted with 1 to 3 fluorine atoms,    -   C₁₋₁₀ alkoxy, optionally substituted with C₁₋₃ alkoxy or 1 to 3        fluorine atoms,    -   C₂₋₆ alkenyloxy,    -   C₁₋₄ alkylthio,    -   C₁₋₈ alkylcarbonyloxy,    -   aryloxycarbonyl,    -   azido,    -   amino,    -   C₁₋₄ alkylamino, and    -   di(C₁₋₄ alkyl)amino; or-   R² is hydrogen, C₂₋₄ alkenyl, C₂₋₄ alkynyl, or C₁₋₄ alkyl optionally    substituted with amino, hydroxy, or 1 to 3 fluorine atoms and one of    R¹ and R³ is hydroxy or C₁₋₄ alkoxy and the other of R¹ and R³ is    selected from the group consisting of    -   hydrogen,    -   hydroxy,    -   halogen,    -   C₁₋₄ alkyl, optionally substituted with 1 to 3 fluorine atoms,    -   C₁₋₁₀ alkoxy, optionally substituted with hydroxy, C₁₋₃ alkoxy,        carboxy, or 1 to 3 fluorine atoms,    -   C₂₋₆ alkenyloxy,    -   C₁₋₄ alkylthio,    -   C₁₋₈ alkylcarbonyloxy,    -   aryloxycarbonyl,    -   azido,    -   amino,    -   C₁₋₄ alkylamino, and    -   di(C₁₋₄ alkyl)amino; or-   R¹ and R² together with the carbon atom to which they are attached    form a 3- to 6-membered saturated monocyclic ring system optionally    containing a heteroatom selected from O, S, and NC₀₋₄ alkyl;-   each R⁴ is independently H, OH, SH, NH₂, C₁₋₄ alkylamino, di(C₁₋₄    alkyl)amino, C₃₋₆ cycloalkylamino, halogen, C₁₋₄ alkyl, C₁₋₄ alkoxy,    or CF₃;-   R⁴ and R⁶ are each independently H, OH, SH, NH₂, C₁₋₄ alkylamino,    di(C₁₋₄ alkyl)amino, C₃₋₆ cycloalkylamino, halogen, C₁₋₄ alkyl, C₁₋₄    alkoxy, or CF₃;-   R⁵ is H, C₁₋₆ alkyl, C₂₋₆ alkenyl, C₂₋₆ alkynyl, C₁₋₄ alkylamino,    CF₃, or halogen;-   R¹⁴ is H, CF₃, C₁₋₄ alkyl, amino, C₁₋₄ alkylamino, C₃₋₆    cycloalkylamino, or di(C₁₋₄ alkyl)amino;-   R⁷ is hydrogen, amino, C₁₋₄ alkylamino, C₃₋₆ cycloalkylamino, or    di(C₁₋₄ alkyl)amino;-   each R¹¹ is independently H or C₁₋₆ alkyl;-   R⁸ is H, halogen, CN, carboxy, C₁₋₄ alkyloxycarbonyl, N₃, amino,    C₁₋₄ alkylamino, di(C₁₋₄ alkyl)amino, hydroxy, C₁₋₆ alkoxy, C₁₋₆    alkylthio, C₁₋₆ alkylsulfonyl, or (C₁₋₄ alkyl)₀₋₂ aminomethyl;-   R¹² and R¹³ are each independently hydrogen, methyl, hydroxymethyl,    or fluoromethyl; and-   R⁹ and R¹⁰ are each independently hydroxy, OCH₂CH₂SC(═O)C₁₋₄ alkyl,    OCH₂O(C═O)OC₁₋₄ alkyl, NHCHMeCO₂Me, OCH(C₁₋₄ alkyl)O(C═O)C₁₋₄ alkyl,    provided that at least one of R⁹ and R¹⁰ is not hydroxy.

The present invention further provides novel compounds of structuralformula XII of the indicated stereochemical configuration which areuseful as inhibitors of RNA-dependent RNA viral polymerase and inparticular of HCV NS5B polymerase:

wherein R^(a) and R^(h) are each independently selected from the groupconsisting of hydrogen, cyano, azido, halogen, hydroxy, mercapto, amino,C₁₋₄ alkoxy, C₂₋₄ alkenyl, C₂₋₄ alkynyl, and C₁₋₄ alkyl, wherein alkylis unsubstituted or substituted with hydroxy, amino, C₁₋₄ alkoxy, C₁₋₄alkylthio, or one to three fluorine atoms;

-   R^(b) is C₂₋₄ alkenyl, C₂₋₄ alkynyl, or C₁₋₄ alkyl, wherein alkyl is    unsubstituted or substituted with hydroxy, amino, C₁₋₄ alkoxy, C₁₋₄    alkylthio, or one to three fluorine atoms;-   R^(c) is hydrogen, fluorine, hydroxy, mercapto, C₁₋₄ alkoxy, or C₁₋₄    alkyl; or R^(b) and-   R^(c) together with the carbon atom to which they are attached form    a 3- to 6-membered saturated monocyclic ring system optionally    containing a heteroatom selected from O, S, and NC₀₋₄ alkyl;-   R^(d) is hydrogen, cyano, nitro, C₁₋₃ alkyl, NHCONH₂, CONRjRj,    CSNRjRj, COORj, C(═NH)NH₂, hydroxy, C₁₋₃ alkoxy, amino, C₁₋₄    alkylamino, di(C₁₋₄ alkyl)amino, halogen, (1,3-oxazol-2-yl),    (1,3-thiazol-2-yl), or (imidazol-2-yl); wherein alkyl is    unsubstituted or substituted with one to three groups independently    selected from halogen, amino, hydroxy, carboxy, and C₁₋₃ alkoxy;-   R^(e) and R^(f) are each independently hydrogen, hydroxy, halogen,    C₁₋₄ alkoxy, amino, C₁₋₄ alkylamino, di(C₁₋₄ alkyl)amino, C₃₋₆    cycloalkylamino, di(C₃₋₆ cycloalkyl)amino, or C₄₋₆ cycloheteroalkyl,    unsubstituted or substituted with one to two groups independently    selected from halogen, hydroxy, amino, C₁₋₄ alkyl, and C₁₋₄ alkoxy;-   R^(g) is hydrogen, C₁₋₄ alkyl, C₂₋₄ alkynyl, halogen, cyano,    carboxy, C₁₋₄ alkyloxycarbonyl, azido, amino, C₁₋₄ alkylamino,    di(C₁₋₄ alkyl)amino, hydroxy, C₁₋₆ alkoxy, C₁₋₆ alkylthio, C₁₋₆    alkylsulfonyl, (C₁₋₄ alkyl)₀₋₂ aminomethyl, or C₄₋₆    cycloheteroalkyl, unsubstituted or substituted with one to two    groups independently selected from halogen, hydroxy, amino, C₁₋₄    alkyl, and C₁₋₄ alkoxy;-   R^(i) is hydrogen, C₁₋₁₀ alkylcarbonyl, P₃O₉H₄, P₂O₆H₃, or    P(O)R^(m)R^(n);-   each R^(i) is independently hydrogen or C₁₋₆ alkyl;-   R^(k) and R^(l) are each independently hydrogen, methyl,    hydroxymethyl, or fluoromethyl; and-   R^(m) and R^(n) are each independently hydroxy, OCH₂CH₂SC(═O)C₁₋₄    alkyl, OCH₂O(C═O)OC₁₋₄ alkyl, NHCHMeCO₂Me, OCH(C₁₋₄ alkyl)O(C═O)C₁₋₄    alkyl,    with the proviso that when R^(a) and R^(c) are α-hydroxy, R^(e) is    amino, R^(b) is β-methyl and R^(h) is hydrogen or R^(h) is β-methyl    and R^(b) is hydrogen, and R^(f), R^(g), R^(i), R^(k), and R^(l) are    hydrogen, then R^(d) is not cyano or CONH₂.

The compounds of formula XII are also inhibitors of RNA-dependent RNAviral replication and in particular of HCV replication and are usefulfor the treatment of RNA-dependent RNA viral infection and in particularfor the treatment of HCV infection.

Also encompassed within the present invention are pharmaceuticalcompositions containing the compounds alone or in combination with otheragents active against RNA-dependent RNA virus and in particular againstHCV.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a method for inhibiting RNA-dependent RNAviral polymerase, a method for inhibiting RNA-dependent RNA viralreplication, and/or a method for treating RNA-dependent RNA viralinfection in a mammal in need thereof comprising administering to themammal a therapeutically effective amount of a compound of structuralformula I which is of the stereochemical configuration:

or a pharmaceutically acceptable salt thereof,wherein B is selected from the group consisting of

-   A, G, and L are each independently CH or N;-   D is N, CH, C—CN, C—NO₂, C—C₁₋₃ alkyl, C—NHCONH₂, C—CONR¹¹R¹¹,    C—CSNR¹¹R¹¹, C—COOR¹¹, C—C(═NH)NH₂, C-hydroxy, C—C₁₋₃ alkoxy,    C-amino, C—C₁₋₄ alkylamino, C-di(C₁₋₄ alkyl)amino, C-halogen,    C-(1,3-oxazol-2-yl), C-(1,3-thiazol-2-yl), or C-(imidazol-2-yl);    wherein alkyl is unsubstituted or substituted with one to three    groups independently selected from halogen, amino, hydroxy, carboxy,    and C₁₋₃ alkoxy;-   E is N or CR⁵;-   W is O or S;-   Y is H, C₁₋₁₀ alkylcarbonyl, P₃O₉H₄, P₂O₆H₃, or P(O)R⁹R¹⁰;-   R¹ is hydrogen, C₂₋₄ alkenyl, C₂₋₄ alkynyl, or C₁₋₄ alkyl optionally    substituted with amino, hydroxy, or 1 to 3 fluorine atoms and one of    R² and R³ is hydroxy or C₁₋₄ alkoxy and the other of R² and R³ is    selected from the group consisting of    -   hydrogen,    -   hydroxy,    -   halogen,    -   C₁₋₄ alkyl, optionally substituted with 1 to 3 fluorine atoms,    -   C₁₋₁₀ alkoxy, optionally substituted with C₁₋₃ alkoxy or 1 to 3        fluorine atoms,    -   C₂₋₆ alkenyloxy,    -   C₁₋₄ alkylthio,    -   C₁₋₈ alkylcarbonyloxy,    -   aryloxycarbonyl,    -   azido,    -   amino,    -   C₁₋₄ alkylamino, and    -   di(C₁₋₄ alkyl)amino; or-   R² is hydrogen, C₂₋₄ alkenyl, C₂₋₄ alkynyl, or C₁₋₄ alkyl optionally    substituted with amino, hydroxy, or 1 to 3 fluorine atoms and one of    R¹ and R³ is hydroxy or C₁₋₄ alkoxy and the other of R¹ and R³ is    selected from the group consisting of    -   hydrogen,    -   hydroxy,    -   halogen,    -   C₁₋₄ alkyl, optionally substituted with 1 to 3 fluorine atoms;    -   C₁₋₁₀ alkoxy, optionally substituted with hydroxy, C₁₋₃ alkoxy,        carboxy, or 1 to 3 fluorine atoms,    -   C₂₋₆ alkenyloxy,    -   C₁₋₄ alkylthio,    -   C₁₋₈ alkylcarbonyloxy,    -   aryloxycarbonyl,    -   azido,    -   amino,    -   C₁₋₄ alkylamino, and    -   di(C₁₋₄ alkyl)amino; or-   R¹ and R² together with the carbon atom to which they are attached    form a 3- to 6-membered saturated monocyclic ring system optionally    containing a heteroatom, selected from O, S, and NC₀₋₄ alkyl;-   R⁴ and R⁶ are each independently H, OH, SH, NH₂, C₁₋₄ alkylamino,    di(C₁₋₄ alkyl)amino, C₃₋₆ cycloalkylamino, halogen, C₁₋₄alkyl, C₁₋₄    alkoxy, or CF₃;-   R⁵ is H, C₁₋₆ alkyl, C₂₋₆ alkenyl, C₂₋₆ alkynyl, C₁₋₄ alkylamino,    CF₃, or halogen;-   R¹⁴ is H, CF₃, C₁₋₄ alkyl, amino, C₁₋₄ alkylamino, C₃₋₆    cycloalkylamino, or di(C₁₋₄ alkyl)amino;-   R⁷ is hydrogen, amino, C₁₋₄ alkylamino, C₃₋₆ cycloalkylamino, or    di(C₁₋₄ alkyl)amino;-   each R¹¹ is independently H or C₁₋₆ alkyl;-   R⁸ is H, halogen, CN, carboxy, C₁₋₄ alkyloxycarbonyl, N₃, amino,    C₁₋₄ alkylamino, di(C₁₋₄ alkyl)amino, hydroxy, C₁₋₆ alkoxy, C₁₋₆    alkylthio, C₁₋₆ alkylsulfonyl, or (C₁₋₄ alkyl)₀₋₂ aminomethyl;-   R¹² and R¹³ are each independently hydrogen, methyl, hydroxymethyl,    or fluoromethyl; and-   R⁹ and R¹⁰ are each independently hydroxy, OCH₂CH₂SC(═O)C₁₋₄ alkyl,    OCH₂O(C═O)OC₁₋₄ alkyl, NHCHMeCO₂Me, OCH(C₁₋₄ alkyl)O(C═O)C₁₋₄ alkyl,    with the provisos that (a) when R¹ is hydrogen, one of R³ and R⁴ is    hydrogen, and R² is fluoro, then the other of R3 and R⁴ is not    hydrogen, halogen, azido, trifluoromethyl, C₁₋₄ alkyl, amino, C₁₋₄    alkylamino, di(C₁₋₄ alkyl)amino, or C₁₋₁₀ alkoxy; (b) when R¹ is    hydrogen, one of R³ and R⁴ is hydrogen, and R² is halogen, hydroxy,    C₁₋₆ alkoxy, or C₂₋₆ alkenyloxy, then the other of R³ and R⁴ is not    hydrogen, fluoro, or azido; and (c) when R¹ and R³ are hydrogen and    R² is hydroxy, then R⁴ is not hydroxy.

In one embodiment of the present invention is the method of inhibitingRNA-dependent RNA viral polymerase, inhibiting RNA-dependent viralreplication, and/or treating RNA-dependent RNA viral infection with acompound of structural formula II which is of the stereochemicalconfiguration:

wherein B is

-   D is N, CH, C—CN, C—NO₂, C—C₁₋₃ alkyl, C—NHCONH₂, C—CONR¹¹R¹¹,    C—CSNR¹¹R¹¹, C—COOR¹¹, C-hydroxy, C—C₁₋₃ alkoxy, C-amino, C—C₁₋₄    alkylamino, C-di(C₁₋₄ alkyl)amino, C-halogen, C-(1,3-oxazol-2-yl),    C-(1,3-thiazol-2-yl), or C-(imidazol-2-yl);-   wherein alkyl is unsubstituted or substituted with one to three    groups independently selected from halogen, amino, hydroxy, carboxy,    and C₁₋₃ alkoxy;-   E is N or C-R⁵;-   W is O or S;-   Y is H, C₁₋₁₀ alkylcarbonyl, P₃O₉H₄, or P(O)R⁹R¹⁰;-   R¹ is hydrogen, CF₃, or C₁₋₄ alkyl and one of R² and R³ is OH or    C₁₋₄ alkoxy and the other of R² and R³ is selected from the group    consisting of    -   hydrogen,    -   hydroxy,    -   halogen,    -   C₁₋₃ alkyl,    -   trifluoromethyl,    -   C₁₋₄ alkoxy,    -   C₁₋₄ alkylthio,    -   C₁₋₈ alkylcarbonyloxy,    -   aryloxycarbonyl,    -   azido,    -   amino,    -   C₁₋₄ alkylamino, and    -   di(C₁₋₄ alkyl)amino; or-   R² is hydrogen, CF₃, or C₁₋₄ alkyl and one of R¹ and R³ is OH or    C₁₋₄ alkoxy and the other of R¹ and R³ is selected from the group    consisting of    -   hydrogen,    -   hydroxy,    -   fluoro,    -   C₁₋₄ alkyl,    -   trifluoromethyl,    -   C₁₋₄ alkoxy,    -   C₁₋₄ alkylthio,    -   C₁₋₈ alkylcarbonyloxy,    -   azido,    -   amino,    -   C₁₋₄ alkylamino, and    -   di(C₁₋₄ alkyl)amino; or-   R¹ and R² together with the carbon atom to which they are attached    form a 3- to 6-membered saturated monocyclic ring system optionally    containing a heteroatom selected from O, S, and NC₀₋₄ alkyl;-   R⁴ and R⁶ are each independently H, OH, SH, NH₂, C₁₋₄ alkylamino,    di(C₁₋₄ alkyl)amino, C₃₋₆ cycloalkylamino, halogen, C₁₋₄ alkyl, C₁₋₄    alkoxy, or CF₃;-   R⁵ is H, C₁₋₆ alkyl, C₂₋₆ alkenyl, C₂₋₆ alkynyl, C₁₋₄ alkylamino,    CF₃, or halogen;-   R⁷ is hydrogen, amino, C₁₋₄ alkylamino, C₃₋₆ cycloalkylamino, or    di(C₁₋₄ alkyl)amino;-   each R¹¹ is independently H or C₁₋₆ alkyl;-   R⁸ is H, halogen, CN, carboxy, C₁₋₄ alkyloxycarbonyl, N₃, amino,    C₁₋₄ alkylamino, di(C₁₋₄ alkyl)amino, hydroxy, C₁₋₆ alkoxy, C₁₋₆    alkylthio, C₁₋₆ alkylsulfonyl, or (C₁₋₄ alkyl)₀₋₂ aminomethyl;-   R¹² and R¹³ are each independently hydrogen or methyl; and-   R⁹ and R¹⁰ are each independently hydroxy, OCH₂CH₂SC(═O)C₁₋₄ alkyl,    or OCH₂O(C═O)C₁₋₄ alkyl;-   with the provisos that (a) when R¹ is hydrogen, one of R³ and R⁴ is    hydrogen, and R² is fluoro, then the other of R³ and R⁴ is not    hydrogen, halogen, trifluoromethyl, C₁₋₄ alkyl, amino, C₁₋₄    alkylamino, di(C₁₋₄ alkyl)amino, or C₁₋₄ alkoxy; (b) when R¹ is    hydrogen, one of R³ and R⁴ is hydrogen, and R² is halogen, hydroxy,    or C₁₋₄ alkoxy, then the other of R³ and R⁴ is not hydrogen, fluoro,    or azido; and (c) when R¹ and R³ are hydrogen and R² is hydroxy,    then R⁴ is not hydroxy.

In a second embodiment of the present invention is the method ofinhibiting RNA-dependent RNA viral polymerase, inhibiting RNA-dependentRNA viral replication, and/or treating RNA-dependent RNA viral infectionwith a compound of structural formula III which is of the stereochemicalconfiguration:

wherein B is

-   D is N, CH, C—CN, C—NO2, C—C₁₋₃ alkyl, C—NHCONH₂, C—CONR¹¹R¹¹,    C—CSNR¹¹R¹¹, C—COOR¹¹, C-hydroxy, C—C₁₋₃ alkoxy, C-amino, C—C₁₋₄    alkylamino, C-di(C₁₋₄ alkyl)amino, C-halogen, C-(1,3-6oxazol-2-yl),    C-(1,3-thiazol-2-yl), or C-(imidazol-2-yl); wherein alkyl is    unsubstituted or substituted with one to three groups independently    selected from halogen, amino, hydroxy, carboxy, and-   C₁₋₃ alkoxy;-   W is O or S;-   Y is H, C₁₋₁₀ alkylcarbonyl, P₃O₉H₄, P₂O₆H₃, or P(O)R⁹R¹⁰;-   R¹ is hydrogen, CF₃, or C₁₋₄ alkyl and one of R² and R³ is OH or    C₁₋₄ alkoxy and the other of R² and R³ is selected from the group    consisting of    -   hydrogen,    -   hydroxy,    -   fluoro,    -   C₁₋₃ alkyl,    -   trifluoromethyl,    -   C₁₋₈ alkylcarbonyloxy,    -   C₁₋₃ alkoxy, and    -   amino; or-   R² is hydrogen, CF₃, or C₁₋₄ alkyl and one of R¹ and R³ is OH or    C₁₋₄ alkoxy and the other of R¹ and R³ is selected from the group    consisting of    -   hydrogen,    -   hydroxy,    -   fluoro,    -   C₁₋₃ alkyl,    -   trifluoromethyl,    -   C₁₋₈ alkylcarbonyloxy,    -   C₁₋₃ alkoxy, and    -   amino; or-   R¹ and R² together with the carbon atom to which they are attached    form a 3- to 6-membered saturated monocyclic ring system optionally    containing a heteroatom selected from O, S, and NC₀₋₄ alkyl;-   R⁶ is H, OH, SH, NH₂, C₁₋₄ alkylamino, di(C₁₋₄ alkyl)amino, C₃₋₆    cycloalkylamino, halogen, C₁₋₄ alkyl, C₁₋₄ alkoxy, or CF₃;-   R⁵ is H, C₁₋₆ alkyl, C₂₋₆ alkenyl, C₂₋₆ alkynyl, C₁₋₄ alkylamino,    CF₃, or halogen;-   R⁷ is hydrogen, amino, C₁₋₄ alkylamino, C₃₋₆ cycloalkylamino, or    di(C₁₋₄ alkyl)amino;-   each R¹¹ is independently H or C₁₋₆ alkyl;-   R⁸ is H, halogen, CN, carboxy, C₁₋₄ alkyloxycarbonyl, N₃, amino,    C₁₋₄ alkylamino, di(C₁₋₄ alkyl)amino, hydroxy, C₁₋₆ alkoxy, C₁₋₆    alkylthio, C₁₋₆ alkylsulfonyl, or (C₁₋₄ alkyl)₀₋₂ aminomethyl; and-   R⁹ and R¹⁰ are each independently hydroxy, OCH₂CH₂SC(═O)t-butyl, or    OCH₂O(C═O)iPr;-   with the provisos that (a) when R¹ is hydrogen and R² is fluoro,    then R³ is not hydrogen, trifluoromethyl, fluoro, C₁₋₃ alkyl, amino,    or C₁₋₃ alkoxy; (b) when R¹ is hydrogen and R² is fluoro, hydroxy,    or C₁₋₃ alkoxy, then R³ is not hydrogen or fluoro; and (c) when R¹    is hydrogen and R² is hydroxy, then R³ is not β-hydroxy.

In a class of this embodiment is the method of inhibiting RNA-dependentRNA viral polymerase, inhibiting RNA-dependent RNA viral replication,and/or treating RNA-dependent RNA viral infection with a compound ofstructural formula III wherein B is

and W, Y, and the R substituents are as defined under this secondembodiment.

In a second class of this embodiment is the method of inhibitingRNA-dependent RNA viral polymerase, inhibiting RNA-dependent RNA viralreplication, and/or treating RNA-dependent RNA viral infection with acompound of structural formula m wherein B is

and Y, D, and the R substituents are as defined under this secondembodiment.

In a third embodiment of the present-invention, the RNA-dependent RNAviral polymerase is a positive-sense single-stranded RNA-dependent RNAviral polymerase. In a class of this embodiment, the positive-sensesingle-stranded RNA-dependent RNA viral polymerase is a Flaviviridaeviral polymerase or a Picornaviridae viral polymerase. In a subclass ofthis class, the Picornaviridae viral polymerase is rhinoviruspolymerase, poliovirus polymerase, or hepatitis A virus polymerase. In asecond subclass of this class, the Flaviviridae viral polymerase isselected from the group consisting of hepatitis C virus polymerase,yellow fever virus polymerase, dengue virus polymerase, West Nile viruspolymerase, Japanese encephalitis virus polymerase, Banzi viruspolymerase, and bovine viral diarrhea virus (BVDV) polymerase. In asubclass of this subclass, the Flaviviridae viral polymerase ishepatitis C virus polymerase.

In a fourth embodiment of the present invention, the RNA-dependent RNAviral replication is a positive-sense single-stranded RNA-dependent RNAviral replication. In a class of this embodiment, the positive-sensesingle-stranded RNA-dependent RNA viral replication is Flaviviridaeviral replication or Picornaviridae viral replication. In a subclass ofthis class, the Picornaviridae viral replication is rhinovirusreplication, poliovirus replication, or hepatitis A virus replication.In a second subclass of this classy the Flaviviridae viral replicationis selected from the group consisting of hepatitis C virus replication,yellow fever virus replication, dengue virus replication, West Nilevirus replication, Japanese encephalitis virus replication, Banzi virusreplication, and bovine viral diarrhea virus replication. In a subclassof this subclass, the Flaviviridae viral replication is hepatitis Cvirus replication.

In a fifth embodiment of the present invention, the RNA-dependent RNAviral infection is a positive-sense single-stranded RNA-dependent viralinfection. In a class of this embodiment, the positive-sensesingle-stranded RNA-dependent RNA viral infection is Flaviviridae viralinfection or Picornaviridae viral infection. In a subclass of thisclass, the Picornaviridae viral infection is rhinovirus infection,poliovirus infection, or hepatitis A virus infection. In a secondsubclass of this class, the Flaviviridae viral infection is selectedfrom the group consisting of hepatitis C virus infection, yellow fevervirus infection, dengue virus infection, West Nile virus infection,Japanese encephalitis virus infection, Banzi virus infection, and bovineviral diarrhea virus infection. In a subclass of this subclass, theFlaviviridae viral infection is hepatitis C virus infection.

Illustrative of the invention is a method for inhibiting RNA-dependentRNA viral polymerase, inhibiting RNA-dependent RNA viral replication,and/or treating RNA-dependent RNA viral infection wherein the compoundis selected from:

-   2′-O-methyl-cytidine,-   2′-C-methyl-cytidine,-   3′,5′-di-O-octanoyl-2′-O-methyl-cytidine,-   3′-O-octanoyl-2′-O-methyl-cytidine,-   2′-C-methyl-adenosine,-   8-amino-2′-C-methyladenosine,-   4-amino-7-(2-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine-5-carbonitrile,-   4-amino-7-(2-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine-5-carboxamide,-   3′-deoxy-3′-methyl-cytidine,-   4-amino-7-(3-deoxy-3-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-5-carboxamide,-   3′-deoxy-adenosine,-   4-amino-7-(3-deoxy-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine,-   4-amino-7-(3-deoxy-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-5-carboxamide,-   3′-amino-3′-deoxyadenosine,-   2-amino-3,4-dihydro-4-oxo-7-(β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-5-carboxamide,-   4-amino-7-(β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-5-carboxamide,-   2-amino-3,4-dihydro-4-oxo-7-(13-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-5-carbonitrile,-   2-amino-5-ethyl-7-(β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-one,-   6-amino-1-(β-D-ribofuranosyl)-1H-imidazo[4,5-c]pyridin-4(5H)-one,    3′-deoxyguanosine,-   2-amino-7-(3-deoxy-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-one,-   2′-O-methylguanosine,-   2-amino-7-(2-O-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-one,-   2-amino-7-(2-O-methyl-β-D-ribofuranosyl)-5H-pyrrolo[3,2-d]pyrimidin-4(3H)-one,-   7-(2-O-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine,-   3′-deoxycytidine,-   2-amino-5-methyl-7-(β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-one,-   2-amino-3,4-dihydro-4-oxo-7-(2-O-methyl-β-D-ribofuranosyl)-7H-pyrrolo-[2,3-d]pyrimidin-5-carbonitrile,-   2-amino-5-methyl-7-(2-O-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-one,-   8-azidoguanosine,-   8-aminoguanosine,-   8-bromoadenosine,-   8-aminoadenosine,-   8-bromoguanosine,-   3′-deoxy-3′-fluorocytidine,-   3′-deoxy-3′-fluoroguanosine,-   4-amino-7-(3-deoxy-3-fluoro-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-5-carboxamide,-   2-amino-4-chloro-7-(2-O-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-5-carbonitrile,-   2-amino-4-chloro-5-ethyl-7-(2-O-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine,-   2-amino-4-chloro-5-methyl-7-(2-O-methyl-β-D-ribofuranosyl)-7H-pyrrolo-[2,3-d]pyrimidine,-   2-amino-7-(2-O-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-thione,-   2-amino-4-chloro-7-(2-O-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine,-   2-amino-7-(β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine,-   2-amino-4-chloro-7-(β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine,-   2-amino-4-chloro-5-methyl-7-(β-D-ribofuranosyl)-7H-pyrrolo[2,3-]pyrimidine,-   1-(β-D-ribofuranosyl)-1H-pyrazolo[3,4-d]pyrimidin-4(3H)-one,-   4-amino-1-(β-D-ribofuranosyl)-1H-pyrazolo[3,4-d]pyrimidine,-   2-amino-6-chloro-9-(β-D-ribofuranosyl)-9H-purine,-   2-amino-4-chloro-7-(β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-5-carbonitrile,-   6-methyl-9-(β-D-ribofuranosyl)-9H-purine,-   2-amino-7-(2-deoxy-2-fluoro-β-D-arabinofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-one,-   2-amino-4-chloro-7-(2-deoxy-2-fluoro-β-D-arabinofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine,-   2-amino-7-(β-D-arabinofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-one,-   2-amino-7-(β-D-arabinofuranosyl)-3,4-dihydro-4-oxo-7H-pyrrolo[2,3-d]pyrimidin-5-carbonitrile,-   2-amino-5-methyl-7-(β-D-arabinofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-one,-   9-(β-D-arabinofuranosyl)-9H-purin-6(1H)-one,-   1-(β-D-arabinofuranosyl)-1H-cytosine,-   2-amino-4-chloro-5-methyl-7-(β-D-arabinofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine,-   3′-deoxy-3′-(fluoromethyl)-guanosine,-   2′-amino-2′-deoxycytidine,-   4-amino-7-(3-deoxy-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-5-carbonitrile,-   2′-O-methyladenosine,-   4-amino-7-(2-O-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine,-   3′-amino-3′-deoxy-2′-O-methyl-adenosine,-   3′-deoxy-3′-methyl-uridine,-   6-amino-1-(3-deoxy-β-D-ribofuranosyl)-1H-imidazo[4,5-c]pyridin-4(5H)-one,-   6-amino-1-(3-deoxy-3-fluoro-β-D-ribofuranosyl)-1H-imidazo[4,5-c]pyridin-4(3H)-one,-   3′-deoxy-3′-fluorouridine,-   3′-deoxy-3′-fluoroadenosine,-   2-amino-7-(2-deoxy-β-D-ribofuranosyl)-3,4-dihydro-4-oxo-7H-pyrrolo[2,3-d]-pyrimidin-5-carbonitrile,-   3′-deoxy-5-methyl-uridine,-   3′-deoxy-2′-O-(2-methoxyethyl)-3′-methyl-5-methyluridine,-   2′-amino-2′-deoxy-uridine,-   2-amino-9-(β-D-arabinofuranosyl)-9H-purin-6(1H)-one,-   3′-deoxy-3′-methylguanosine,-   2′-O-[4-(imidazolyl-1)butyl]guanosine,-   2′-deoxy-2′-fluoroguanosine,-   2′-deoxyguanosine,-   2-amino-7-(2-deoxy-2-fluoro-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-one,-   2-amino-7-(3-deoxy-β-D-ribofuranosyl)-3,4-dihydro-4-oxo-7H-pyrrolo[2,3-d]pyrimidin-5-carbonitrile,-   2-amino-5-iodo-7-(β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-one,-   2-amino-7-(3-deoxy-3-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-5-carbonitrile,-   2-amino-7-(β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-one,-   2-amino-7-(2-deoxy-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-one,-   2-amino-7-(3-deoxy-3-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-one,-   2-amino-7-(3-deoxy3-fluoro-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-one,-   6-amino-1-(2-O-methyl-β-D-ribofuranosyl)-1H-imidazo[4,5-c]pyridin-4(5H)-one,-   6-amino-1-(2-deoxy-β-D-ribofuranosyl)-1H-imidazo[4,5-c]pyridin-4(5H)-one,-   6-amino-1-(3-deoxy-3-methyl-β-D-ribofuranosyl)-1H-imidazo[4,5-c]pyridin-4(5H)-one,-   6-amino-1-(2-deoxy-2-fluoro-β-D-ribofuranosyl)-1H-imidazo[4,5-c]pyridin-4(5H)-one,-   6-amino-1-(β-D-arabinofuranosyl)-1H-imidazo[4,5-c]pyridin-4(5H)-one,-   2′-O-[2-(N,N-diethylaminooxy)ethyl]-5-methyluridine,-   5-ethynyl-2′-O-(2-methoxyethyl)-cytidine,-   1-(2-C-methyl-β-D-arabinofuranosyl)uracil,-   5-methyl-3′-deoxycytidine,-   2-amino-2′-O-methyladenosine,-   2′-deoxy-2′-fluoroadenosine,-   3′-deoxy-3′-fluoroadenosine,-   3′-deoxy-3′-methyladenosine,-   2-amino-7-(2-deoxy-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine,-   4-amino-7-(3-deoxy-3-fluoro-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-5-carboxamide,-   4-amino-7-(3-deoxy-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-5-carboxamide,-   4-amino-7-(2-O-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine,-   4-amino-7-(β-D-arabinofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine,-   4-amino-1-(3-deoxy-3-fluoro-β-D-ribofuranosyl)-1H-imidazo[4,5-c]pyridine,-   4-amino-7-(β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine    (tubercidin),-   4,6-diamino-7-(13-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine,-   2-amino-7-(3-deoxy-3-fluoro-β-D-ribofuranosyl)-7H-pyrrolo-[2,3-d]pyrimidin-5-carboxamide,-   4-amino-1-(3-deoxy-β-D-ribofuranosyl)-1H-imidazo[4,5-c]pyridine,-   4-amino-1-(3-deoxy-3-methyl-β-D-ribofuranosyl)-1H-imidazo[4,5-c]pyridine,-   4-amino-1-(β-D-ribofuranosyl)-1H-imidazo[4,5-c]pyridine,-   4-amino-1-(2-C-methyl-β-D-ribofuranosyl)-1H-pyrazolo[3,4-d]pyrimidine,-   4-amino-7-(3-deoxy-3-fluoro-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine;    and-   the corresponding 5′-triphosphates,    5′-[bis(isopropyloxycarbonyloxymethyl)]monophosphates,    5′-mono-(S-C₁₋₄ alkanoyl-2-thioethyl)monophosphates, and    5′-bis-(S-C₁₋₄ alkanoyl-2-thioethyl)monophosphates thereof;    or a pharmaceutically acceptable salt thereof.

Further illustrative of the invention is a method for inhibitingRNA-dependent RNA viral polymerase, inhibiting RNA-dependent RNA viralreplication, and/or treating RNA-dependent RNA viral infection whereinthe compound is selected from:

-   2′-O-methyl-cytidine,-   2′-C-methyl-cytidine,-   3′,5′-di-O-octanoyl-2′-O-methyl-cytidine,-   3′-O-octanoyl-2′-O-methyl-cytidine,-   4-amino-1-(β-D-ribofuranosyl)-1H-pyrazolo[3,4-d]pyrimidine,-   4-amino-7-(2-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine-5-carbonitrile,-   4-amino-7-(2-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine-5-carboxamide,-   2′-C-methyladenosine,-   8-amino-2′-C-methyladenosine,-   3′-deoxy-3′-methyl-cytidine,-   4-amino-7-(3-deoxy-3-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-5-carboxamide,-   3′-deoxyadenosine,-   4-amino-7-(3-deoxy-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine,-   4-amino-7-(3-deoxy-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-5-carboxamide,-   3′-amino-3′-deoxyadenosine,-   2-amino-3,4-dihydro-4-oxo-7-(β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-5-carboxamide,-   4-amino-7-(β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-5-carboxamide,-   2-amino-3,4-dihydro-4-oxo-7-(β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-5-carbonitrile,-   2-amino-5-ethyl-7-(β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-one,-   6-amino-1-(β-D-ribofuranosyl)-1H-imidazo[4,5-c]pyridin-4(5H)-one,-   3′-deoxyguanosine,-   2-amino-7-(3-deoxy-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-one,-   2′-O-methylguanosine,-   2-amino-7-(2-O-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-one,-   2-amino-7-(2-O-methyl-β-D-ribofuranosyl)-5H-pyrrolo[3    ,2-d]pyrimidin-4-(3H)-one,-   7-(2-O-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine,-   3′-deoxy-cytidine,-   2-amino-5-methyl-7-(β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-one,-   2-amino-3,4-dihydro-4-oxo-7-(2-O-methyl-β-D-ribofuranosyl)-7H-pyrrolo-[2,3-d]pyrimidine-5-carbonitrile,-   2-amino-5-methyl-7-(2-O-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-one,-   8-azidoguanosine,-   8-aminoguanosine,-   8-bromoadenosine,-   8-aminoadenosine,-   8-bromoguanosine,-   3′-deoxy-3′-fluorocytidine,-   3′-deoxy-3′-fluoroguanosine,-   4-amino-7-(3-deoxy-3-fluoro-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]-pyrimidin-5-carboxamide,-   2-amino-4-chloro-7-(2-O-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-5-carbonitrile,-   2-amino-4-chloro-5-ethyl-7-(2-O-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine,-   2-amino-4-chloro-5-methyl-7-(2-O-methyl-β-D-ribofuranosyl)-7H-pyrrolo-[2,3-d]pyrimidine,-   2-amino-7-(β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine,-   2-amino-4-chloro-7-(β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine,-   2-amino-4-chloro-5-methyl-7-(β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine,-   2-amino-7-(2-deoxy-2-fluoro-β-D-arabinofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-one,-   4-amino-1-(2-C-methyl-β-D-ribofuranosyl)-1H-pyrazolo[3,4-d]pyrimidine,-   2-amino-7-(β-D-arabinofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-one,    and-   2-amino-7-(β-D-arabinofuranosyl)-3,4-dihydro-4-oxo-7H-pyrrolo[2,3-d]pyrimidin-5-carbonitrile;    and-   the corresponding 5′-triphosphates,    5′-[bis(isopropyloxycarbonyloxymethyl)]monophosphates,    5′-mono-(S-pivaloyl-2-thioethyl)monophosphates, and    5′-bis-(S-pivaloyl-2-thioethyl)monophosphates thereof;    or a pharmaceutically acceptable salt thereof.

Even further illustrative of the present invention is a method forinhibiting RNA-dependent RNA viral polymerase, inhibiting RNA-dependentRNA viral replication, and/or treating RNA-dependent RNA viral infectionwherein the compound is selected from

-   2′-O-methyl-cytidine,-   2′-C-methyl-cytidine,-   3′,5′-di-O-octanoyl-2′-O-methyl-cytidine,-   3′-O-octanoyl-2′-O-methyl-cytidine,-   4-amino-1-(β-D-ribofuranosyl)-1H-pyrazolo[3,4-d]pyrimidine,-   4-amino-7-(2-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine-5-carbonitrile,-   4-amino-7-(2-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine-5-carboxamide,-   2′-C-methyladenosine,-   8-amino-2′-C-methyladenosine,-   8-bromoguanosine,-   8-aminoguanosine,-   8-aminoadenosine,-   4-amino-7-(3-deoxy-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine,-   2-amino-4-chloro-5-ethyl-7-(2-O-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine,-   2-amino-3,4-dihydro-4-oxo-7-(β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-5-carboxamide,-   4-amino-1-(2-C-methyl-β-D-ribofuranosyl)-1H-pyrazolo[3,4-d]pyrimidine,-   2-amino-4-chloro-7-(2-O-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-5-carbonitrile;    and the corresponding 5′-triphosphates thereof;-   2′-O-methylcytidine-5′-[bis-(S-pivaloyl-2-thioethyl)phosphate],-   2-amino-7-(3-deoxy-β-D-ribofuranosyl)-3,4-dihydro-4-oxo-7H-pyrrolo[2,3-d]pyrimidine-5′-[bis-(S-pivaloyl-2-thioethyl)phosphate],-   3′-deoxyguanosine-5′-[bis-(S-pivaloyl-2-thioethyl)phosphate], and-   3′-deoxycytidine-5′-[bis-(S-pivaloyl-2-thioethyl)phosphate];    or a pharmaceutically acceptable salt thereof.

Yet further illustrative of the invention is a method for inhibitingRNA-dependent RNA viral polymerase, inhibiting RNA-dependent RNA viralreplication, and/or treating RNA-dependent RNA viral infection whereinthe compound is selected from:

-   2′-O-methylcytidine,-   2′-C-methylcytidine,-   3′,5′-di-O-octanoyl-2′-O-methyl-cytidine,-   3′-O-octanoyl-2′-O-methyl-cytidine,-   4-amino-7-(2-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine-5-carbonitrile,-   4-amino-7-(2-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine-5-carboxamide,-   2′-C-methyladenosine,-   8-amino-2′-C-methyladenosine,-   2′-O-methylcytidine-5′-[bis-(S-pivaloyl-2-thioethyl)phosphate],-   2-amino-7-(3-deoxy-β-D-ribofuranosyl)-3,4-dihydro-4-oxo-7H-pyrrolo[2,3-d]pyrimidine-5′-[bis-(S-pivaloyl-2-thioethyl)phosphate],    and-   3′-deoxycytidine-5′-[bis-(S-pivaloyl-2-thioethyl)phosphate];    or a pharmaceutically acceptable salt thereof.

The present invention also provides novel compounds of structuralformula IV of the indicated stereochemical configuration which areuseful as inhibitors of RNA-dependent RNA viral polymerase:

wherein B is selected from the group consisting of

-   A, G, and L are each independently CH or N;-   D is N, CH, C—CN, C—NO₂, C—C₁₋₃ alkyl, C—NHCONH₂, C—CONR¹¹R¹¹,    C—CSNR¹¹R¹¹, C—COOR¹¹, C-hydroxy, C—C₁₋₃ alkoxy, C-amino, C—C₁₋₄    alkylamino, C-di(C₁₋₄ alkyl)amino, C-halogen, C-(1,3-oxazol-2-yl),    C-(1,3-thiazol-2-yl), or C-(imidazol-2-yl); wherein alkyl is    unsubstituted or substituted with one to three groups independently    selected from halogen, amino, hydroxy, carboxy, and-   C₁₋₃ alkoxy;-   E is N or CR⁵;-   W is O or S;-   R¹ is hydrogen, C₂₋₄ alkenyl, C₂₋₄ alkynyl, or C₁₋₄ alkyl optionally    substituted with amino, hydroxy, or 1 to 3 fluorine atoms and one of    R² and R³ is hydroxy or C₁₋₄ alkoxy and the other of R² and R³ is    selected from the group consisting of    -   hydrogen,    -   hydroxy,    -   halogen,    -   C₁₋₄ alkyl, optionally substituted with 1 to 3 fluorine atoms,    -   C₁₋₁₀ alkoxy, optionally substituted with C₁₋₃ alkoxy of 1 to 3        fluorine atoms,    -   C₂₋₆ alkenyloxy,    -   C₁₋₄ alkylthio,    -   C₁₋₈ alkylcarbonyloxy,    -   aryloxycarbonyl,    -   azido,    -   amino,    -   C₁₋₄ alkylamino, and    -   di(C₁₋₄ alkyl)amino; or-   R² is hydrogen, C₂₋₄ alkenyl, C₂₋₄ alkynyl, or C₁₋₄ alkyl optionally    substituted with amino, hydroxy, or 1 to 3 fluorine atoms and one of    R¹ and R³ is hydroxy or C₁₋₄ alkoxy and the other of R¹ and R³ is    selected from the group consisting of    -   hydrogen,    -   hydroxy,    -   halogen,    -   C₁₋₄ alkyl, optionally substituted with 1 to 3 fluorine atoms,    -   C₁₋₁₀ alkoxy, optionally substituted with hydroxy, C₁₋₃ alkoxy,        carboxy, or 1 to 3 fluorine atoms,    -   C₂₋₆ alkenyloxy,    -   C₁₋₄ alkylthio,    -   C₁₋₈ alkylcarbonyloxy,    -   aryloxycarbonyl,    -   azido,    -   amino,    -   C₁₋₄ alkylamino, and    -   di(C₁₋₄ alkyl)amino; or-   R¹ and R² together with the carbon atom to which they are attached    form a 3- to 6-membered saturated monocyclic ring system optionally    containing a heteroatom selected from O, S, and NC₀₋₄ alkyl;-   R⁴ and R⁶ are each independently H, OH, SH, NH₂, C₁₋₄ alkylamino,    di(C₁₋₄ alkyl)amino, C₃₋₆ cycloalkylamino, halogen, C₁₋₄ alkyl, C₁₋₄    alkoxy, or CF₃;-   R⁵ is H, C₁₋₆ alkyl, C₂₋₆ alkenyl, C₂₋₆ alkynyl, C₁₋₄ alkylamino,    CF₃, or halogen;-   R¹⁴ is H, CF₃, C₁₋₄ alkyl, amino, C₁₋₄ alkylamino, C₃₋₆    cycloalkylamino, or di(C₁₋₄ alkyl)amino;-   R⁷ is hydrogen, amino, C₁₋₄ alkylamino, C₃₋₆ cycloalkylamino, or    di(C₁₋₄ alkyl)amino;-   each R¹¹ is independently H or C₁₋₆ alkyl;-   R⁸ is H, halogen, CN, carboxy, C₁₋₄ alkyloxycarbonyl, N₃, amino,    C₁₋₄ alkylamino, di(C₁₋₄ alkyl)amino, hydroxy, C₁₋₆ alkoxy, C₁₋₆    alkylthio, C₁₋₆ alkylsulfonyl, or (C₁₋₄ alkyl)₀₋₂ aminomethyl;-   R¹² and R¹³ are each independently hydrogen or methyl; and-   R⁹ and R¹⁰ are each independently hydroxy, OCH₂CH₂SC(═O)C₁₋₄ alkyl,    OCH₂O(C═O)OC₁₋₄ alkyl, NHCHMeCO₂Me, OCH(C₁₋₄ alkyl)O(C═O)C₁₋₄ alkyl,    provided that at least one of R⁹ and R¹⁰ is not hydroxy.

The compounds of formula IV are also inhibitors of RNA-dependent RNAviral replication and are useful for the treatment of RNA-dependent RNAviral infection.

In one embodiment, there are provided novel compounds of structuralformula V which are of the stereochemical configuration:

wherein B is

-   D is N, CH, C—CN, C—NO₂, C—C₁₋₃ alkyl, C—NHCONH₂, C—CONR¹¹R¹¹,    C—CSNR¹¹R¹¹, C—COOR¹¹, C-hydroxy, C—C₁₋₃ alkoxy, C-amino, C—C₁₋₄    alkylamino, C-di(C₁₋₄ alkyl)amino, C-halogen, C-(1,3-oxazol-2-yl),    C-(1,3-thiazol-2-yl), or C-(imidazol-2-yl); wherein alkyl is    unsubstituted or substituted with one to three groups independently    selected from halogen, amino, hydroxy, carboxy, and-   C₁₋₃ alkoxy;-   W is O or S;-   E is N or C-R⁵;-   R¹ is hydrogen, C₂₋₄ alkenyl, C₂₋₄ alkynyl, or C₁₋₄ alkyl optionally    substituted with amino, hydroxy, or 1 to 3 fluorine atoms and one of    R² and R³ is hydroxy or C₁₋₄ alkoxy and the other of R² and R³ is    selected from the group consisting of    -   hydrogen,    -   hydroxy,    -   halogen,    -   C₁₋₃ alkyl,    -   trifluoromethyl,    -   C₁₋₄ alkoxy,    -   C₁₋₄ alkylthio,    -   C₁₋₈ alkylcarbonyloxy,    -   aryloxycarbonyl,    -   azido,    -   amino,    -   C₁₋₄ alkylamino, and    -   di(C₁₋₄ alkyl)amino, or,-   R² is hydrogen, C₂₋₄ alkenyl, C₂₋₄ alkynyl, or C₁₋₄ alkyl optionally    substituted with amino, hydroxy, or 1 to 3 fluorine atoms and one of    R¹ and R³ is hydroxy or C₁₋₄ alkoxy and the other of R¹ and R³ is    selected from the group consisting of    -   hydrogen,    -   hydroxy,    -   fluoro,    -   C₁₋₄ alkyl,    -   trifluoromethyl,    -   C₁₋₄ alkoxy,    -   C₁₋₄ alkylthio,    -   C₁₋₈ alkylcarbonyloxy,    -   azido,    -   amino,    -   C₁₋₄ alkylamino, and    -   di(C₁₋₄ alkyl)amino; or-   R¹ and R² together with the carbon atom to which they are attached    form a 3- to 6-membered saturated monocyclic ring system optionally    containing a heteroatom selected from O, S, and NC₀₋₄ alkyl;-   R⁴ and R⁶ are each independently H, OH, SH, NH₂, C₁₋₄ alkylamino,    di(C₁₋₄ alkyl)amino, C₃₋₆ cycloalkylamino, halogen, C₁₋₄ alkyl, C₁₋₄    alkoxy, or CF₃;-   R⁵ is H, C₁₋₆ alkyl, C₂₋₆ alkenyl, C₂₋₆ alkynyl, C₁₋₄ alkylamino,    CF₃, or halogen;-   R⁷ is hydrogen, amino, C₁₋₄ alkylamino, C₃₋₆ cycloalkylamino, or    di(C₁₋₄ alkyl)amino;-   each R¹¹ is independently H or C₁₋₆ alkyl;-   R⁸ is H, halogen, CN, carboxy, C₁₋₄ alkyloxycarbonyl, N₃, amino,    C₁₋₄ alkylamino, di(C₁₋₄ alkyl)amino, hydroxy, C₁₋₆ alkoxy, C₁₋₆    alkylthio, C₁₋₆ alkylsulfonyl, or-   (C₁₋₄ alkyl)₀₋₂ aminomethyl; and-   R⁹ and R¹⁰ are each independently hydroxy, OCH₂CH₂SC(═O)C₁₋₄ alkyl,    or OCH₂O(C═O)C₁₋₄ alkyl, provided that at least one of R⁹ and R¹⁰ is    not hydroxy.

In a second embodiment, there are provided novel compounds of structuralformula VI:

wherein B is

-   D is N, CH, C—CN, C—NO₂, C—C₁₋₃ alkyl, C—NHCONH₂, C—CONR¹¹R¹¹,    C—CSNR¹¹R¹¹, C—COOR¹¹, C-hydroxy, C—C₁₋₃ alkoxy, C-amino, C—C₁₋₄    alkylamino, C-di(C₁₋₄ alkyl)amino, C-halogen, C-(1,3-oxazol-2-yl),    C-(1,3-thiazol-2-yl), or C-(imidazol-2-yl); wherein alkyl is    unsubstituted or substituted with one to three groups independently    selected from halogen, amino, hydroxy, carboxy, and-   C₁₋₃ alkoxy;-   W is O or S;-   R¹ is hydrogen, C₂₋₄ alkenyl, C₂₋₄ alkynyl, or C₁₋₄ alkyl optionally    substituted with amino, hydroxy, or 1 to 3 fluorine atoms and one of    R² and R³ is hydroxy or C₁₋₄ alkoxy and the other of R² and R³ is    selected from the group consisting of    -   hydrogen,    -   hydroxy,    -   fluoro,    -   C₁₋₃ alkyl,    -   trifluoromethyl,    -   C₁₋₃ alkoxy,    -   C₁₋₈ alkylcarbonyloxy, and    -   amino; or-   R² is hydrogen, C₂₋₄ alkenyl, C₂₋₄ alkynyl, or C₁₋₄ alkyl optionally    substituted with amino, hydroxy, or 1 to 3 fluorine atoms and one of    R¹ and R³ is hydroxy or C₁₋₄ alkoxy and the other of R¹ and R³ is    selected from the group consisting of    -   hydrogen,    -   hydroxy,    -   fluoro,    -   C₁₋₃ alkyl,    -   trifluoromethyl,    -   C₁₋₃ alkoxy,    -   C₁₋₈ alkylcarbonyloxy, and    -   amino; or-   R¹ and R² together with the carbon atom to which they are attached    form a 3- to 6-membered saturated monocyclic ring system optionally    containing a heteroatom selected from O, S, and NC₀₋₄ alkyl,-   R⁶ is H, OH, SH, NH₂, C₁₋₄ alkylamino, di(C₁₋₄ alkyl)amino, C₃₋₆    cycloalkylamino, halogen, C₁₋₄ alkyl, C₁₋₄ alkoxy, or CF₃;-   R⁵ is H, C₁₋₆ alkyl, C₂₋₆ alkenyl, C₂₋₆ alkynyl, C₁₋₄ alkylamino,    CF₃, or halogen;-   R⁷ is hydrogen, amino, C₁₋₄ alkylamino, C₃₋₆ cycloalkylamino, or    di(C₁₋₄ alkyl)amino;-   each R¹¹ is independently H or C₁₋₆ alkyl;-   R⁸ is H, halogen, CN, carboxy, C₁₋₄ alkyloxycarbonyl, N₃, amino,    C₁₋₄ alkylamino, di(C₁₋₄ alkyl)amino, hydroxy, C₁₋₆ alkoxy, C₁₋₆    alkylthio, C₁₋₆ alkylsulfonyl, or (C₁₋₄ alkyl)₀₋₂ aminomethyl; and-   R⁹ and R¹⁰ are each independently hydroxy, OCH₂CH₂SC(═O)t-butyl, or    OCH₂O(C═O)iPr, provided that at least one of R⁹ and R¹⁰ is not    hydroxy.

Illustrative of the novel compounds of structural formula VI of thepresent invention are the following:

-   2′-O-methylcytidine-5′-[bis-(S-pivaloyl-2-thioethyl)phosphate],-   2-amino-7-(3-deoxy-β-D-ribofuranosyl)-3,4-dihydro-4-oxo-7H-pyrrolo[2,3-d]pyrimidine-5′-[bis-(S-pivaloyl-2-thioethyl)phosphate],-   3′-deoxyguanosine-5′-[bis-(S-pivaloyl-2-thioethyl)phosphate],-   2′-O-methylguanosine-5′-[bis-(S-acetyl-2-thioethyl)phosphate],-   2′-O-methylguanosine-5′-[bis-(S-pivaloyl-2-thioethyl)phosphate],-   8-bromo-2′-O-methylguanosine-5′-[bis-(S-pivaloyl-2-thioethyl)phosphate],-   2-amino-3,4-dihydro-7-(2-O-methyl-β-D-ribofuranosyl)4-oxo-7H-pyrrolo[2,3-d]pyrimidine-5′-[bis-(S-pivaloyl-2-thioethyl)phosphate],-   2-amino-5-bromo-7-(3-deoxy-β-D-ribofuranosyl)-3,4-dihydro-4-oxo-7H-pyrrolo[2,3-d]pyrimidine-5′-[bis-(S-pivaloyl-2-thioethyl)phosphate],-   5-bromo-2′-O-methylcytidine-5′-[bis-(S-pivaloyl-2-thioethyl)phosphate],-   3-deoxycytidine-5′-[bis-(S-pivaloyl-2-thioethyl)phosphate], and-   2′-O-methylcytidine-5′-[bis(isopropyloxycarbonyloxymethyl)]phosphate.

The present invention further provides novel compounds of structuralformula XII of the indicated stereochemical configuration or apharmaceutically acceptable salt thereof which are useful as inhibitorsof RNA-dependent RNA viral polymerase:

wherein R^(a) and R^(h) are each independently selected from the groupconsisting of hydrogen, cyano, azido, halogen, hydroxy, mercapto, amino,C₁₋₄ alkoxy, C₂₋₄ alkenyl, C₂₋₄ alkynyl, and C₁₋₄ alkyl, wherein alkylis unsubstituted or substituted with hydroxy, amino, C₁₋₄ alkoxy, C₁₋₄alkylthio, or one to three fluorine atoms;

-   R^(b) is C₂₋₄ alkenyl, C₂₋₄ alkynyl, or C₁₋₄ alkyl, wherein alkyl is    unsubstituted or substituted with hydroxy, amino, C₁₋₄ alkoxy, C₁₋₄    alkylthio, or one to three fluorine atoms;-   R^(c) is hydrogen, fluorine, hydroxy, mercapto, C₁₋₄ alkoxy, or C₁₋₄    alkyl; or R^(b) and R^(c) together with the carbon atom to which    they are attached form a 3- to 6-membered saturated monocyclic ring    system optionally containing a heteroatom selected from O, S, and    NC₀₋₄ alkyl;-   R^(d) is hydrogen, cyano, nitro, C₁₋₃ alkyl, NHCONH₂, CONRjRj,    CSNRjRj, COORj, C(═NH)NH₂, hydroxy, C₁₋₃ alkoxy, amino, C₁₋₄    alkylamino, di(C₁₋₄ alkyl)amino, halogen, (1,3-oxazol-2-yl),    (1,3-thiazol-2-yl), or (imidazol-2-yl); wherein alkyl is    unsubstituted or substituted with one to three groups independently    selected from halogen, amino, hydroxy, carboxy, and C₁₋₃ alkoxy;-   R^(e) and R^(f) are each independently hydrogen, hydroxy, halogen,    C₁₋₄ alkoxy, amino, C₁₋₄ alkylamino, di(C₁₋₄ alkyl)amino, C₃₋₆    cycloalkylamino, di(C₃₋₆ cycloalkyl)amino, or C₄₋₆ cycloheteroalkyl,    unsubstituted or substituted with one to two groups independently    selected from halogen, hydroxy, amino, C₁₋₄ alkyl, and C₁₋₄ alkoxy;-   R^(g) is hydrogen, C₁₋₄ alkyl, C₂₋₄ alkynyl, halogen, cyano,    carboxy, C₁₋₄ alkyloxycarbonyl, azido, amino, C₁₋₄ alkylamino,    di(C₁₋₄ alkyl)amino, hydroxy, C₁₋₆ alkoxy, C₁₋₆ alkylthio, C₁₋₆    alkylsulfonyl, (C₁₋₄ alkyl)₀₋₂ aminomethyl, or C₄₋₆    cycloheteroalkyl, unsubstituted or substituted with one to two    groups independently selected from halogen, hydroxy, amino, C₁₋₄    alkyl, and C₁₋₄ alkoxy;-   R^(i) is hydrogen, C₁₋₁₀ alkylcarbonyl, P₃O₉H₄, P₂O₆H₃, or    P(O)R^(m)R^(n);-   each R^(j) is independently hydrogen or C₁₋₆ alkyl;-   R^(k) and R^(l) are each independently hydrogen, methyl,    hydroxymethyl, or fluoromethyl; and-   R^(m) and R^(n) are each independently hydroxy, OCH₂CH₂SC(═O)C₁₋₄    alkyl, OCH₂O(C═O)OC₁₋₄ alkyl, NHCHMeCO₂Me, OCH(C₁₋₄ alkyl)O(C═O)C₁₋₄    alkyl,    with the proviso that when R^(a) and R^(c) are α-hydroxy, R^(e) is    amino, R^(b) is β-methyl and R^(h) is hydrogen or R^(h) is β-methyl    and R^(b) is hydrogen, and R^(f), R^(g), R^(i), R^(k), and R^(l) are    hydrogen, then R^(d) is not cyano or CONH₂.

The compounds of formula XII are also inhibitors of RNA-dependent RNAviral replication and are useful for the treatment of RNA-dependent RNAviral infection.

In one embodiment of the novel compounds of structural formula XII arethe compounds of structural formula XIII:

-   wherein R^(a) is hydrogen, halogen, hydroxy, amino, or C₁₋₃ alkoxy;-   R^(b) is C₁₋₃ alkyl, wherein alkyl is unsubstituted or substituted    with hydroxy, amino, C₁₋₃ alkoxy, C₁₋₃ alkylthio, or one to three    fluorine atoms;-   R^(c) is hydroxy, fluoro, or C₁₋₄ alkoxy;-   R^(d) is hydrogen, cyano, methyl, halogen, or CONH₂;-   R^(g) is hydrogen, amino, or C₁₋₄ alkylamino;-   R^(i) is hydrogen, P₃O₉H₄, P₂O₆H₃, or PO₃H₂; and-   R^(e) and R^(f) are each independently hydrogen, hydroxy, halogen,    amino, C₁₋₄ alkylamino, di(C₁₋₄ alkyl)amino, or C₃₋₆    cycloalkylamino;-   with the proviso that when R^(a) and R^(c) are α-hydroxy, R^(e) is    amino, R^(b) is methyl, and R^(f), R^(g), and R^(i) are hydrogen,    then R^(d) is not cyano or CONH₂.

In a second embodiment of the compounds of structural formula XII arethe compounds of structural formula XIII wherein:

-   R^(b) is methyl, fluoromethyl, hydroxymethyl, difluoromethyl,    trifluoromethyl, or aminomethyl;-   R^(c) is hydroxy, fluoro, or methoxy;-   R^(a) is hydrogen, fluoro, hydroxy, amino, or methoxy;-   R^(i) is hydrogen or P₃O₉H₄;-   R^(g) is hydrogen or amino;-   R^(d) is hydrogen, cyano, methyl, halogen, or CONH₂; and-   R^(e) and R^(f) are each independently hydrogen, fluoro, hydroxy, or    amino;-   with the proviso that when R^(b) is β-methyl, R^(a) and R^(c) are    α-hydroxy, R^(e) is amino, and-   R^(f), R^(g), and R^(i) are hydrogen, then R^(d) is not cyano or    CONH₂.

Illustrative of the novel compounds of the present invention ofstructural formula XIII which are useful as inhibitors of RNA-dependentRNA viral polymerase are the following:

-   4-amino-7-(2-C-methyl-β-D-arabinofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine,-   4-amino-7-(2-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine,-   4-methylamino-7-(2-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine,-   4-dimethylamino-7-(2-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine,-   4-cyclopropylamino-7-(2-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine,-   4-amino-7-(2-C-vinyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine,-   4-amino-7-(2-C-hydroxymethyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine,-   4-amino-7-(2-C-fluoromethyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine,-   4-amino-5-methyl-7-(2-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine,-   4-amino-7-(2-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine-5-carboxylic    acid,-   4-amino-5-bromo-7-(2-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine,-   4-amino-5-chloro-7-(2-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine,-   4-amino-5-fluoro-7-(2-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine,-   2,4-diamino-7-(2-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine,-   2-amino-7-(2-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine,-   2-amino-4-cyclopropylamino-7-(2-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine,-   2-amino-7-(2-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-one,-   4-amino-7-(2-C-ethyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine,-   4-amino-7-(2-C,2-O-dimethyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine,-   7-(2-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-one,-   2-amino-5-methyl-7-(2-C,2-O-dimethyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-one,-   4-amino-7-(3-deoxy-2-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine,-   4-amino-7-(3-deoxy-2-C-methyl-β-D-arabinofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine,-   4-amino-2-fluoro-7-(2-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine,-   4-amino-7-(3-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine,-   4-amino-7-(3-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine,-   4-amino-7-(2,4-di-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine,    and-   4-amino-7-(3-deoxy-3-fluoro-2-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine;    and the corresponding 5′-triphosphates;    or a pharmaceutically acceptable salt thereof.

Further illustrative of the novel compounds of the present invention ofstructural formula XIII which are useful as inhibitors of RNA-dependentRNA viral polymerase are the following:

-   4-amino-7-(2-C-methyl-β-D-arabinofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine,-   4-amino-7-(2-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine,-   4-amino-7-(2-C-fluoromethyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine,-   4-amino-5-methyl-7-(2-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine,-   4-amino-5-bromo-7-(2-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine,-   4-amino-5-chloro-7-(2-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine,-   4-amino-5-fluoro-7-(2-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine,    and-   4-amino-7-(2-C,2-O-dimethyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine,    and the corresponding 5′-triphosphates;    or a pharmaceutically acceptable salt thereof.

Further structurally novel nucleoside derivatives of the presentinvention which are useful as inhibitors of RNA-dependent RNA viralpolymerase are the following:

-   3′-deoxy-3′-methyl-cytidine,-   3′,5-di-O-octanoyl-2′-O-methyl-cytidine,-   3′-O-octanoyl-2′-O-methyl-cytidine,-   4-amino-7-(3-deoxy-3-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-5-carboxamide,-   2-amino-5-ethyl-7-(β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-one,-   2-amino-7-(3-deoxy-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-one,-   2-amino-7-(2-O-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-one,-   -2-amino-7-(2-O-methyl-β-D-ribofuranosyl)-5H-pyrrolo[3    ,2-d]pyrimidin-4(3H)-one,-   7-(2-O-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine,-   2-amino-3,4-dihydro-4-oxo-7-(2-O-methyl-β-D-ribofuranosyl)-7H-pyrrolo-[2,3-d]pyrimidin-5-carbonitrile,-   2-amino-5-methyl-7-(2-O-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-one,-   2-amino-4-chloro-7-(2-O-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-5-carbonitrile,-   2-amino-4-chloro-5-ethyl-7-(2-O-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine,-   2-amino-4-chloro-5-methyl-7-(2-O-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine,-   2-amino-7-(2-O-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyridin-4(3H)-thione,-   2-amino-4-chloro-7-(2-O-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine,-   2-amino-4-chloro-5-methyl-7-(β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine,-   2-amino-7-(2-deoxy-2-fluoro-β-D-arabinofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-one,-   2-amino-4-chloro-7-(2-deoxy-2-fluoro-β-D-arabinofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine,-   2-amino-7-(β-D-arabinofuranosyl)-3,4-dihydro-4-oxo-7H-pyrrolo[2,3-d]pyrimidin-5-carbonitrile,-   9-(β-D-arabinofuranosyl)-9H-purin-6(1H)-one,-   3′-amino-3′-deoxy-2′-O-methyl-adenosine,-   8-amino-2′-C-methyladenosine,-   6-amino-1-(3-deoxy-β-D-ribofuranosyl)-1H-imidazo[4,5-c]pyridin-4(5H)-one,-   6-amino-1-(3-deoxy-3-fluoro-β-D-ribofuranosyl)-1H-imidazo[4,5-c]pyridin-4(3H)-one,-   3′-deoxy-2′-O-(2-methoxyethyl)-3′-methyl-5-methyluridine,-   2-amino-7-(3-deoxy-β-D-ribofuranosyl)-3,4-dihydro-4oxo-7H-pyrrolo[2,3-d]pyrimidin-5-carbonitrile,-   2-amino-7-(3-deoxy-3-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyridin-5-carbonitrile,-   2-amino-7-(3-deoxy-3-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyridin-4(3H)-one,-   2-amino-7-(3-deoxy-3-fluoro-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-one,-   6-amino-1-(2-O-methyl-β-D-ribofuranosyl)-1H-imidazo[4,5-c]pyridin-4(5H)-one,-   6-amino-1-(3-deoxy-3-methyl-β-D-ribofuranosyl)-1H-imidazo[4,5-c]pyridin-4(5H)-one,-   6-amino-1-(2-deoxy-2-fluoro-β-D-ribofuranosyl)-1H-imidazo[4,5-c]pyridin-4(5H)-one,-   1-(2-C-methyl-β-D-arabinofuranosyl)uracil,-   4-amino-1-(3-deoxy-3-fluoro-β-D-ribofuranosyl)-1H-imidazo[4,5-c]pyridine,-   2-amino-7-(-3-deoxy-3-fluoro-β-D-ribofuranosyl)-7H-pyrrolo-[2,3-d]pyrimidin-5-carboxamide,-   4-amino-1-(2-C-methyl-β-D-ribofuranosyl)-1H-pyrazolo[3,4-d]pyrimidine,-   4-amino-1-(3-deoxy-β-D-ribofuranosyl)-1H-imidazo[4,5-c]pyridine, and-   4-amino-1-(3-deoxy-3-methyl-β-D-ribofuranosyl)-1H-imidazo[4,5-c]pyridine;    and the corresponding 5′-triphosphates;    or a pharmaceutically acceptable salt thereof.

In a further embodiment the novel compounds of the present invention areuseful as inhibitors of positive-sense single-stranded RNA-dependent RNAviral polymerase, inhibitors of positive-sense single-strandedRNA-dependent RNA viral replication, and/or for the treatment ofpositive-sense single-stranded RNA-dependent RNA viral infection. In aclass of this embodiment, the positive-sense single-strandedRNA-dependent RNA virus is a Flaviviridae virus or a Picornaviridaevirus. In a subclass of this class, the Picornaviridae virus is arhinovirus, a poliovirus, or a hepatitis A virus. In a second subclassof this class, the Flaviviridae virus is selected from the groupconsisting of hepatitis C virus, yellow fever virus, dengue virus, WestNile virus, Japanese encephalitis virus, Banzi virus, and bovine viraldiarrhea virus (BVDV). In a subclass of this subclass, the Flaviviridaevirus is hepatitis C virus.

Throughout the instant application, the following terms have theindicated meanings:

The alkyl groups specified above are intended to include those alkylgroups of the designated length in either a straight or branchedconfiguration. Exemplary of such alkyl groups are methyl, ethyl, propyl,isopropyl, butyl, sec-butyl, tertiary butyl, pentyl, isopentyl, hexyl,isohexyl, and the like.

The term “alkenyl” shall mean straight or branched chain alkenes of twoto six total carbon atoms, or any number within this range (e.g.,ethenyl, propenyl, butenyl, pentenyl, etc.).

The term “alkynyl” shall mean straight or branched chain alkynes of twoto six total carbon atoms, or any number within this range (e.g.,ethynyl, propynyl, butynyl, pentynyl, etc.).

The term “cycloalkyl” shall mean cyclic rings of alkanes of three toeight total carbon atoms, or any number within this range (i.e.,cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, orcyclooctyl).

The term “cycloheteroalkyl” is intended to include non-aromaticheterocycles containing one or two heteroatoms selected from nitrogen,oxygen and sulfur. Examples of 4-6-membered cycloheteroalkyl includeazetidinyl, pyrrolidinyl, piperidinyl, morpholinyl, thiamorpholinyl,imidazolidinyl, tetrahydrofuranyl, tetrahydropyranyl,tetrahydrothiophenyl, piperazinyl, and the like.

The term “alkoxy” refers to straight or branched chain alkoxides of thenumber of carbon atoms specified (e.g., C₁₋₄ alkoxy), or any numberwithin this range [i.e., methoxy (MeO—), ethoxy, isopropoxy, etc.].

The term “alkylthio” refers to straight or branched chain alkylsulfidesof the number of carbon atoms specified (e.g., C₁₋₄ alkylthio), or anynumber within this range [i.e., methylthio (MeS—), ethylthio,isopropylthio, etc.].

The term “alkylamino” refers to straight or branched alkylamines of thenumber of carbon atoms specified (e.g., C₁₋₄ alkylamino), or any numberwithin this range [i.e., methylamino, ethylamino, isopropylamino,t-butylamino, etc.].

The term “alkylsulfonyl” refers to straight or branched chainalkylsulfones of the number of carbon atoms specified (e.g., C₁₋₆alkylsulfonyl), or any number within this range [i.e., methylsulfonyl(MeSO₂—), ethylsulfonyl, isopropylsulfonyl, etc.].

The term “alkyloxycarbonyl” refers to straight or branched chain estersof a carboxylic acid derivative of the present invention of the numberof carbon atoms specified (e.g., C₁₋₄ alkyloxycarbonyl), or any numberwithin this range [i.e., methyloxycarbonyl (MeOCO—), ethyloxycarbonyl,or butyloxycarbonyl].

The term “aryl” includes both phenyl, naphthyl, and pyridyl. The arylgroup is optionally substituted with one to three groups independentlyselected from C₁₋₄ alkyl, halogen, cyano, nitro, trifluoromethyl, C₁₋₄alkoxy, and C₁₋₄ alkylthio.

The term “halogen” is intended to include the halogen atoms fluorine,chlorine, bromine and iodine.

The term “substituted” shall be deemed to include multiple degrees ofsubstitution by a named substituent. Where multiple substituent moietiesare disclosed or claimed, the substituted compound can be independentlysubstituted by one or more of the disclosed or claimed substituentmoieties, singly or plurally.

The term “5′-triphosphate” refers to a triphosphoric acid esterderivative of the 5′-hydroxyl group of a nucleoside compound of thepresent invention having the following general structural formula VII:

wherein B, Z, R¹-R⁴, R¹², and R¹³ are as defined above. The compounds ofthe present invention are also intended to include pharmaceuticallyacceptable salts of the triphosphate ester as well as pharmaceuticallyacceptable salts of 5′-monophosphate and 5′-diphosphate esterderivatives of the structural formulae VIII and IX, respectively,

The term “5′-(S-acyl-2-thioethyl)phosphate” or “SATE” refers to a mono-or di-ester derivative of a 5′-monophosphate nucleoside of the presentinvention of structural formulae X and XI, respectively, as well aspharmaceutically acceptable salts of the mono-ester,

The term “composition”, as in “pharmaceutical composition,” is intendedto encompass a product comprising the active ingredient(s) and the inertingredient(s) that make up the carrier, as well as any product whichresults, directly or indirectly, from combination, complexation oraggregation of any two or more of the ingredients, or from dissociationof one or more of the ingredients, or from other types of reactions orinteractions of one or more of the ingredients. Accordingly, thepharmaceutical compositions of the present invention encompass anycomposition made by admixing a compound of the present invention and apharmaceutically acceptable carrier.

The terms “administration of” and “administering a” compound should beunderstood to mean providing a compound of the invention or a prodrug ofa compound of the invention to the individual in need.

Another aspect of the present invention is concerned with a method ofinhibiting HCV NS5B polymerase, inhibiting HCV replication, or treatingHCV infection with a compound of the present invention in combinationwith one or more agents useful for treating HCV infection. Such agentsactive against HCV include, but are not limited to, ribavirin,levovirin, viramidine, thymosin alpha-1, interferon-α, pegylatedinterferon-α peginterferon-α), a combination of interferon-α andribavirin, a combination of peginterferon-α and ribavirin, a combinationof interferon-α and levovirin, and a combination of peginterferon-α andlevovirin. Interferon-α includes, but is not limited to, recombinantinterferon-α2a (such as Roferon interferon available fromHoffman-LaRoche, Nutley, N.J.), pegylated interferon-α2a (Pegasys™),interferon-α2b (such as Intron-A interferon available from ScheringCorp., Kenilworth, N.J.), pegylated interferon-α2b (PegIntron™), arecombinant consensus interferon (such as interferon alphacon-1), and apurified interferon-α product. Amgen's recombinant consensus interferonhas the brand name Infergen®. Levovirin is the L-enantiomer of ribavirinwhich has shown immunomodulatory activity similar to ribavirin.Viramidine is an amino analog of ribavirin disclosed in WO 01/60379(assigned to ICN Pharmaceuticals). In accordance with this method of thepresent invention, the individual components of the combination can beadministered separately at different times during the course of therapyor concurrently in divided or single combination forms. The instantinvention is therefore to be understood as embracing all such regimes ofsimultaneous or alternating treatment, and the term “administering” isto be interpreted accordingly. It will be understood that the scope ofcombinations of the compounds of this invention with other agents usefulfor treating HCV infection includes in principle any combination withany pharmaceutical composition for treating HCV infection. When acompound of the present invention or a pharmaceutically acceptable saltthereof is used in combination with a second therapeutic agent activeagainst HCV, the dose of each compound may be either the same as ordifferent from the dose when the compound is used alone.

For the treatment of HCV infection, the compounds of the presentinvention may also be administered in combination with an agent that isan inhibitor of HCV NS3 serine protease, such as LY570310 (VX-950). HCVNS3 serine protease is an essential viral enzyme and has been describedto be an excellent target for inhibition of HCV replication. Bothsubstrate and non-substrate based inhibitors of HCV NS3 proteaseinhibitors are disclosed in WO 98/17679, WO 98/22496, WO 98/46630, WO99/07733, WO 99/07734, WO 99/38888, WO 99/50230, WO 99/64442, WO00/09543, WO 00/59929, WO 01/74768, WO 01/81325, and GB-2337262. HCV NS3protease as a target for the development of inhibitors of HCVreplication and for the treatment of HCV infection is discussed in B. W.Dymock, “Emerging therapies for hepatitis C virus infection,” EmergingDrugs, 6: 13-42 (2001).

Ribavirin, levovirin, and viramidine may exert their anti-HCV effects bymodulating intracellular pools of guanine nucleotides via inhibition ofthe intracellular enzyme inosine monophosphate dehydrogenase (IMPDH).IMPDH is the rate-limiting enzyme on the biosynthetic route in de novoguanine nucleotide biosynthesis. Ribavirin is readily phosphorylatedintracellularly and the monophosphate derivative is an inhibitor ofIMPDH. Thus, inhibition of IMPDH represents another useful target forthe discovery of inhibitors of HCV replication. Therefore, the compoundsof the present invention may also be administered in combination with aninhibitor of IPDH, such as VX-497, which is disclosed in WO 97/41211 andWO 01/00622, (assigned to Vertex); another IMPDH inhibitor, such as thatdisclosed in WO 00/25780 (assigned to Bristol-Myers Squibb); ormycophenolate mofetil [see A. C. Allison and E. M. Eugui, Agents Action,44 (Suppl.): 165 (1993)].

For the treatment of HCV infection, the compounds of the presentinvention may also be administered in combination with the antiviralagent amantadine (1-aminoadamaitane) [for a comprehensive description ofthis agent, see J. Kirschbaum, Anal. Profiles Drug Subs. 12: 1-36(1983)].

The compounds of the present invention may also be combined for thetreatment of HCV infection with antiviral 2′-C-branched ribonucleosidesdisclosed in R. E. Harry-O'kuru, et al., J. Org. Chem., 62: 1754-1759(1997); M. S. Wolfe, et al., Tetrahedron Lett., 36: 7611-7614 (1995);and U.S. Pat. No. 3,480,613 (Nov. 25, 1969), the contents of which areincorporated by reference in their entirety. Such 2′-C-branchedribonucleosides include, but are not limited to, 2′-C-methyl-cytidine,2′-C-methyl-adenosine, 2′-C-methyl-guanosine, and9-(2-C-methyl-β-D-ribofuranosyl)-2,6-diaminopurine.

By “pharmaceutically acceptable” is meant that the carrier, diluent, orexcipient must be compatible with the other ingredients of theformulation and not deleterious to the recipient thereof.

Also included within the present invention are pharmaceuticalcompositions comprising the novel nucleoside compounds and derivativesthereof of the present invention in association with a pharmaceuticallyacceptable carrier. Another example of the invention is a pharmaceuticalcomposition made by combining any of the compounds described above and apharmaceutically acceptable carrier. Another illustration of theinvention is a process for making a pharmaceutical compositioncomprising combining any of the compounds described above and apharmaceutically acceptable carrier.

Also included within the present invention are pharmaceuticalcompositions useful for inhibiting RNA-dependent RNA viral polymerase inparticular HCV NS5B polymerase comprising an effective amount of acompound of this invention and a pharmaceutically acceptable carrier.Pharmaceutical compositions useful for treating RNA-dependent RNA viralinfection in particular HCV infection are also encompassed by thepresent invention as well as a method of inhibiting RNA-dependent RNAviral polymerase in particular HCV NS5B polymerase and a method oftreating RNA-dependent viral replication and in particular HCVreplication. Additionally, the present invention is directed to apharmaceutical composition comprising a therapeutically effective amountof a compound of the present invention in combination with atherapeutically effective amount of another agent active againstRNA-dependent RNA virus and in particular against HCV. Agents activeagainst HCV include, but are not limited to, ribavirin, levovirin,viramidine, thymosin alpha-1, an inhibitor of HCV NS3 serine protease,interferon-α, pegylated interferon-α peginterferon-α), a combination ofinterferon-α and ribavirin, a combination of peginterferon-α andribavirin, a combination of interferon-α and levovirin, and acombination of peginterferon-α and levovirin. Interferon-α includes, butis not limited to, recombinant interferon-α2a (such as Roferoninterferon available from Hoffmann-LaRoche, Nutley, N.J.),interferon-α2b (such as Intron-A interferon available from ScheringCorp., Kenilworth, N.J.), a consensus interferon, and a purifiedinterferon-α product. For a discussion of ribavirin and its activityagainst HCV, see J. O. Saunders and S. A. Raybuck, “InosineMonophosphate Dehydrogenase: Consideration of Structure, Kinetics, andTherapeutic Potential,” Ann. Rep. Med. Chem., 35: 201-210 (2000).

Another aspect of the present invention provides for the use ofnucleoside compounds and derivatives thereof and their pharmaceuticalcompositions for the manufacture of a medicament for the inhibition ofRNA-dependent RNA viral replication, in particular HCV replication,and/or the treatment of RNA-dependent RNA viral infection, in particularHCV infection. Yet a further aspect of the present invention providesfor nucleoside compounds and derivatives thereof and theirpharmaceutical compositions for use as a medicament for the inhibitionof RNA-dependent RNA viral replication, in particular HCV replication,and/or for the treatment of RNA-dependent RNA viral infection, inparticular HCV infection.

The pharmaceutical compositions of the present invention comprise acompound of structural formula I, IV, or XII as an active ingredient ora pharmaceutically acceptable salt thereof, and may also contain apharmaceutically acceptable carrier and optionally other therapeuticingredients.

The compositions include compositions suitable for oral, rectal,topical, parenteral (including subcutaneous, intramuscular, andintravenous), ocular (ophthalmic), pulmonary (nasal or buccalinhalation), or nasal administration, although the most suitable routein any given case will depend on the nature and severity of theconditions being treated and on the nature of the active ingredient.They may be conveniently presented in unit dosage form and prepared byany of the methods well-known in the art of pharmacy.

In practical use, the compounds of structural formulae I, IV, and XIIcan be combined as the active ingredient in intimate admixture with apharmaceutical carrier according to conventional pharmaceuticalcompounding techniques. The carrier may take a wide variety of formsdepending on the form of preparation desired for administration, e.g.,oral, or parenteral (including intravenous). In preparing thecompositions for oral dosage form, any of the usual pharmaceutical mediamay be employed, such as, for example, water, glycols, oils, alcohols,flavoring agents, preservatives, coloring agents and the like in thecase of oral liquid preparations, such as, for example, suspensions,elixirs and solutions; or carriers such as starches, sugars,microcrystalline cellulose, diluents, granulating agents, lubricants,binders, disintegrating agents and the like in the case of oral solidpreparations such as, for example, powders, hard and soft capsules andtablets, with the solid oral preparations being preferred over theliquid preparations.

Because of their ease of administration, tablets and capsules representthe most advantageous oral dosage unit form in which case solidpharmaceutical carriers are obviously employed. If desired, tablets maybe coated by standard aqueous or nonaqueous techniques. Suchcompositions and preparations should contain at least 0.1 percent ofactive compound. The percentage of active compound in these compositionsmay, of course, be varied and may conveniently be between about 2percent to about 60 percent of the weight of the unit. The amount ofactive compound in such therapeutically useful compositions is such thatan effective dosage will be obtained. The active compounds can also beadministered intranasally as, for example, liquid drops or spray.

The tablets, pills, capsules, and the like may also contain a bindersuch as gum tragacanth, acacia, corn starch or gelatin; excipients suchas dicalcium phosphate; a disintegrating agent such as corn starch,potato starch, alginic acid; a lubricant such as magnesium stearate; anda sweetening agent such as sucrose, lactose or saccharin. When a dosageunit form is a capsule, it may contain, in addition to materials of theabove type, a liquid carrier such as a fatty oil.

Various other materials may be present as coatings or to modify thephysical form of the dosage unit. For instance, tablets may be coatedwith shellac, sugar or both. A syrup or elixir may contain, in additionto the active ingredient, sucrose as a sweetening agent, methyl andpropylparabens as preservatives, a dye and a flavoring such as cherry ororange flavor.

Compounds of structural formulae I, IV, and XII may also be administeredparenterally. Solutions or suspensions of these active compounds can beprepared in water suitably mixed with a surfactant such ashydroxy-propylcellulose. Dispersions can also be prepared in glycerol,liquid polyethylene glycols and mixtures thereof in oils. Under ordinaryconditions of storage and use, these preparations contain a preservativeto prevent the growth of microorganisms.

The pharmaceutical forms suitable for injectable use include sterileaqueous solutions or dispersions and sterile powders for theextemporaneous preparation of sterile injectable solutions ordispersions. In all cases, the form must be sterile and must be fluid tothe extent that easy syringability exists. It must be stable under theconditions of manufacture and storage and must be preserved against thecontaminating action of microorganisms such as bacteria and fungi. Thecarrier can be a solvent or dispersion medium containing, for example,water, ethanol, polyol (e.g. glycerol, propylene glycol and liquidpolyethylene glycol), suitable mixtures thereof, and vegetable oils.

Any suitable route of administration may be employed for providing amammal, especially a human with an effective dosage of a compound of thepresent invention. For example, oral, rectal, topical, parenteral,ocular, pulmonary, nasal, and the like may be employed. Dosage formsinclude tablets, troches, dispersions, suspensions, solutions, capsules,creams, ointments, aerosols, and the like. Preferably compounds ofstructural formulae I, IV, and XII are administered orally.

For oral administration to humans, the dosage range is 0.01 to 1000mg/kg body weight in divided doses. In one embodiment the dosage rangeis 0.1 to 100 mg/kg body weight in divided doses. In another embodimentthe dosage range is 0.5 to 20 mg/kg body weight in divided doses. Fororal administration, the compositions are preferably provided in theform of tablets or capsules containing 1.0 to 1000 milligrams of theactive ingredient, particularly, 1, 5, 10, 15, 20, 25, 50, 75, 100, 150,200, 250, 300, 400, 500, 600, 750, 800, 900, and 1000 milligrams of theactive ingredient for the symptomatic adjustment of the dosage to thepatient to be treated.

The effective dosage of active ingredient employed may vary depending onthe particular compound employed, the mode of administration, thecondition being treated and the severity of the condition being treated.Such dosage may be ascertained readily by a person skilled in the art.This dosage regimen may be adjusted to provide the optimal therapeuticresponse.

The compounds of the present invention contain one or more asymmetriccenters and can thus occur as racemates and racemic mixtures, singleenantiomers, diastereomeric mixtures and individual diastereomers. Thepresent invention is meant to comprehend nucleoside derivatives havingthe β-D stereochemical configuration for the five-membered furanose ringas depicted in the structural formula below, that is, nucleosidecompounds in which the substituents at C-1 and C-4 of the five-memberedfuranose ring have the β-stereochemical configuration (“up” orientationas denoted by a bold line).

The stereochemistry of the substituents at the C-2 and C-3 positions ofthe furanose ring of the compounds of the present invention is denotedeither by a dashed line which signifies that the substituent, forexample R² in structural formula VI, has the a (substituent “down”)configuration or a squiggly line which signifies that the substituent,for example R³ in structural formula VI, can have either the a(substituent “down”) or β (substituent “up”) configuration.

Some of the compounds described herein contain olefinic double bonds,and unless specified otherwise, are meant to include both E and Zgeometric isomers.

Some of the compounds described herein may exist as tautomers such asketo-enol tautomers. The individual tautomers as well as mixturesthereof are encompassed with compounds of structural formulae I, IV, andXII. An example of keto-enol tautomers which are intended to beencompassed within the compounds of the present invention is illustratedbelow:

Compounds of structural formulae I, IV, and XII may be separated intotheir individual diastereoisomers by, for example, fractionalcrystallization from a suitable solvent, for example methanol or ethylacetate or a mixture thereof, or via chiral chromatography using anoptically active stationary phase.

Alternatively, any stereoisomer of a compound of the structural formulaeI, IV, and XII may be obtained by stereospecific synthesis usingoptically pure starting materials or reagents of known configuration.

The stereochemistry of the substituents at the C-2 and C-3 positions ofthe furanose ring of the novel compounds of the present invention ofstructural formula XII is denoted by squiggly lines which signifies thatsubstituents R^(a), R^(b), R^(c) and R^(h) can have either the α(substituent “down”) or β (substituent “up”) configuration independentlyof one another.

The compounds of the present invention may be administered in the formof a pharmaceutically acceptable salt. The term “pharmaceuticallyacceptable salt” refers to salts prepared from pharmaceuticallyacceptable non-toxic bases or acids including inorganic or organic basesand inorganic or organic acids. Salts of basic compounds encompassedwithin the term “pharmaceutically acceptable salt” refer to non-toxicsalts of the compounds of this invention which are generally prepared byreacting the free base with a suitable organic or inorganic acid.Representative salts of basic compounds of the present inventioninclude, but are not limited to, the following: acetate,benzenesulfonate, benzoate, bicarbonate, bisulfate, bitartrate, borate,bromide, camsylate, carbonate, chloride, clavulanate, citrate,dihydrochloride, edetate, edisylate, estolate, esylate, fumarate,gluceptate, gluconate, glutamate, glycollylarsanilate, hexylresorcinate,hydrabamine, hydrobromide, hydrochloride, hydroxynaphthoate, iodide,isothionate, lactate, lactobionate, laurate, malate, maleate, mandelate,mesylate, methylbromide, methylnitrate, methylsulfate, mucate,napsylate, nitrate, N-methylglucamine ammonium salt, oleate, oxalate,pamoate (embonate), palmitate, pantothenate, phosphate/diphosphate,polygalacturonate, salicylate, stearate, sulfate, subacetate, succinate,tannate, tartrate, teoclate, tosylate, triethiodide and valerate.Furthermore, where the compounds of the invention carry an acidicmoiety, suitable pharmaceutically acceptable salts thereof include, butare not limited to, salts derived from inorganic bases includingaluminum, ammonium, calcium, copper, ferric, ferrous, lithium,magnesium, manganic, mangamous, potassium, sodium, zinc, and the like.Particularly preferred are the ammonium, calcium, magnesium, potassium,and sodium salts. Salts derived from pharmaceutically acceptable organicnon-toxic bases include salts of primary, secondary, and tertiaryamines, cyclic amines, and basic ion-exchange resins, such as arginine,betaine, caffeine, choline, N,N-dibenzylethylenediamine, diethylamine,2-diethylaminoethanol, 2-dimethylaminoethanol, ethanolamine,ethylenediamine, N-ethylmorpholine, N-ethylpiperidine, glucamine,glucosamine, histidine, hydrabamine, isopropylamine, lysine,methylglucamine, morpholine, piperazine, piperidine, polyamine resins,procaine, purines, theobromine, triethylamine, trimethylamine,tripropylamine, tromethamine, and the like.

Also, in the case of a carboxylic acid (—COOH) or alcohol group beingpresent in the compounds of the present invention, pharmaceuticallyacceptable esters of carboxylic acid derivatives, such as methyl, ethyl,or pivaloyloxymethyl, or acyl derivatives of alcohols, such as acetateor maleate, can be employed. Included are those esters and acyl groupsknown in the art for modifying the solubility or hydrolysischaracteristics for use as sustained-release or prodrug formulations.

Preparation of the Nucleoside Compounds and Derivatives of the Invention

The nucleoside compounds and derivatives thereof of the presentinvention can be prepared following synthetic methodologieswell-established in the practice of nucleoside and nucleotide chemistry.Reference is made to the following text for a description of syntheticmethods used in the preparation of the compounds of the presentinvention: “Chemistry of Nucleosides and Nucleotides,” L. B. Townsend,ed., Vols. 1-3, Plenum Press, 1988, which is incorporated by referenceherein in its entirety.

A representative general method for the preparation of compounds of thepresent invention is outlined in Scheme 1 below. This scheme illustratesthe synthesis of compounds of the present invention of structuralformula 1-7 wherein the furanose ring has the β-D-ribo configuration.The starting material is a 3,5-bis-O-protected alkyl furanoside, such asmethyl furanoside, of structural formula 1-1. The C-2 hydroxyl group isthen oxidized with a suitable oxidizing agent, such as a chromiumtrioxide or chromate reagent or Dess-Martin periodinane, or by Swernoxidation, to afford a C-2 ketone of structural formula 1-2. Addition ofa Grignard reagent, such as an alkyl, alkenyl, or alkynyl magnesiumhalide (for example, MeMgBr, EtMgBr, vinylMgBr, allylMgBr, andethynylMgBr) or an alkyl, alkenyl, or alkynyl lithium, such as MeLi,across the carbonyl double bond of 1-2 in a suitable organic solvent,such as tetrahydrofuran, diethyl ether, and the like, affords the C-2tertiary alcohol of structural formula 1-3. A good leaving group (suchas Cl, Or, and I) is next introduced at the C-1 (anomeric) position ofthe furanose sugar derivative by treatment of the furanoside of formula1-3 with a hydrogen halide in a suitable organic solvent, such ashydrogen bromide in acetic acid, to afford the intermediate furanosylhalide 1-4. A C-1 sulfonate, such methanesulfonate (MeSO₂O—,trifluoromethanesulfonate (CF₃SO₂O—), or p-toluenesulfonate (—OTs), mayalso serve as a useful leaving group in the subsequent reaction togenerate the glycosidic (nucleosidic) linkage. The nucleosidic linkageis constructed by treatment of the intermediate of structural formula1-4 with the metal salt (such as lithium, sodium, or potassium) of anappropriately substituted 1H-pyrrolo[2,3-d]pyrimidine 1-5, such as anappropriately substituted 4-halo-1H-pyrrolo[2,3-d]pyrimidine, which canbe generated in situ by treatment with an alkali hydride (such as sodiumhydride), an alkali hydroxide (such as potassium hydroxide), an alkalicarbonate (such as potassium carbonate), or an alkalihexamethyldisilazide (such as NaHMDS) in a suitable anhydrous organicsolvent, such as acetonitrile, tetrahydrofuran,1-methyl-2-pyrrolidinone, or N,N-dimethylformamide (DMF). Thedisplacement reaction can be catalyzed by using a phase-transfercatalyst, such as TDA-1 or triethylbenzylammonium chloride, in atwo-phase system (solid-liquid or liquid-liquid). The optionalprotecting groups in the protected nucleoside of structural formula 1-6are then cleaved following established deprotection methodologies, suchas those described in T. W. Greene and P. G. M. Wuts, “Protective Groupsin Organic Synthesis,” 3^(rd) ed., John Wiley & Sons, 1999. Optionalintroduction of an amino group at the 4-position of thepyrrolo[2,3-d]pyrimidine nucleus is effected by treatment of the 4-halointermediate 1-6 with the appropriate amine, such as alcoholic ammoniaor liquid ammonia, to generate a primary amine at the C-4 position(—NH₂), an alkylamine to generate a secondary amine (—NHR), or adialkylamine to generate a tertiary amine (—NRR′). A7H-pyrrolo[2,3-d]pyrimidin-4(3H)one compound may be derived byhydrolysis of 1-6 with aqueous base, such as aqueous sodium hydroxide.Alcoholysis (such as methanolysis) of 1-6 affords a C-4 alkoxide (—OR),whereas treatment with an alkyl mercaptide affords a C-4 alkylthio (—SR)derivative. Subsequent chemical manipulations well-known topractitioners of ordinary skill in the art of organic/medicinalchemistry may be required to attain the desired compounds of the presentinvention.

The examples below provide citations to literature publications, whichcontain details for the preparation of final compounds or intermediatesemployed in the preparation of final compounds of the present invention.The nucleoside compounds of the present invention were preparedaccording to procedures detailed in the following examples. The examplesare not intended to be limitations on the scope of the instant inventionin any way, and they should not be so construed. Those skilled in theart of nucleoside and nucleotide synthesis will readily appreciate thatknown variations of the conditions and processes of the followingpreparative procedures can be used to prepare these and other compoundsof the present invention. All temperatures are degrees Celsius unlessotherwise noted.

EXAMPLE 1 3′-Deoxyguanosine

This compound was prepared following the procedures described inNucleosides Nucleotides, 13: 1049 (1994).

EXAMPLE 2 3′-Deoxy-3′-fluoroguanosine

This compound was prepared following the procedures described in J. Med.Chem. 34: 2195 (1991).

EXAMPLE 3 8-Azidoguanosine

This compound was prepared following the procedures described in Chem.Pharm. Bull..16: 1616 (1968).

EXAMPLE 4 8-Bromoguanosine

This compound was obtained from commercial sources.

EXAMPLE 5 2′-O-Methylguanosine

This compound was obtained from commercial sources.

EXAMPLE 6 3′-Deoxy-3′-(fluoromethyl)guanosine

To a solution of1,2-O-diacetyl-5-O-(p-toluoyl)-3-deoxy-3-(fluoromethyl)-D-ribofuranose(257 mg, 0.7 mmol) [prepared by a similar method as that described forthe corresponding 5-O-benzyl derivative in J Med. Chem. 36: 353 (1993)]and N²-acetyl-O⁶-(diphenylcarbamoyl)guanine (554 mg, 1.43 mmol) inanhydrous acetonitrile (6.3 mL) was added bis(trimethylsilyl)acetamide(BSA) (1.03 g, 5 mmol). The reaction mixture was stirred at reflux for30 minutes, and the bath was removed. The reaction mixture was cooled inan ice bath and TMS-triflate (288 mg, 1.3 mmol) was added with stirring.After addition was complete, the reaction was heated at reflux for 2hr., the reaction mixture was poured onto ice and extracted withchloroform (5×10 mL). The combined organic layers were washed withaqueous saturated sodium bicarbonate, brine and dried over anhydrousNa₂SO₄. The solvent was removed under reduced pressure and the residuechromatographed over silica gel using 5% acetone/CH₂Cl₂ as the eluant tofurnish the fully protected corresponding nucleoside derivative. Thiswas dissolved in 1,4-dioxane (1.5 mL) to which was added 40% MeNH₂/H₂O(1.3 g, 17 mmol). The reaction mixture was stirred for 1 day, evaporatedand the residue crystallized with ether/MeOH to provide the titlecompound (58 mg). ¹H NMR (DMSO-d₆): δ 2.76-2.67 (m, 1H); 3.55-3.50 (m,1H), 2.76-2.67 (m, 1H); 3.71-3.66 (m, 1H), 4.08-4.04 (m, 1H), 4.77-4.50(m, 3H) 5.06 (t, 1H, J=5.3 Hz), 5.69 (d, 1H, J=3.4 Hz), 5.86 (d, 1H,J=5.1 Hz), 6.45 (bs, 2H), 7.97 (s, 1H), 10.59 (s, 1H). ¹⁹F NMR(DMSO-d₆): δ −221.46 (m, F).

EXAMPLE 72-Amino-3,4-dihydro-4-oxo-7-(β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-5-carboxamide

This compound was prepared following the procedures described inTetrahedron. Lett. 25: 4793 (1983).

EXAMPLE 82-Amino-3,4-dihydro-4-oxo-7-(β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-5-carbonitrile

This compound was prepared following the procedures described in J. Am.Chem. Soc. 98: 7870 (1976).

EXAMPLE 92-Amino-5-ethyl-7-(β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-one

Step A:2-Amino-7-(5-O-tert-butyldimethylsilyl-2,3-O-isopropylidene-β-D-ribofuranosyl)-4-chloro-5H-pyrrolo[2,3-d]pyrimidine

To a stirred suspension of2-amino-4-chloro-5-ethyl-1H-pyrrolo[2,3-d]pyrimidine [described in EP866070 (1998)] (1.57 g, 8 mmol) in dry MeCN (48 mL) was added NaH (60%in mineral oil; 0.32 g, 8 mmol), and the mixture was stirred at roomtemperature for 1 h. A solution of5-O-tert-butyldimethylsilyl-2,3-O-isopropylidene-α-D-ribofuranosylchloride [generated in situ from the corresponding lactol (1.95 g, 6.4mmol) according to Wilcox et al., Tetrahedron Lett., 27: 1011 (1986)] indry THF (9.6 mL) was added at room temperature, and the mixture wasstirred overnight, then evaporated to dryness. The residue was suspendedin water (100 mL) and extracted with EtOAc (200+150 mL). The combinedextracts were washed with brine, dried (Na₂SO₄) and evaporated. Theresidue was purified on a silica gel column using a solvent system ofhexanes/EtOAc: 7/1. Appropriate fractions were collected and evaporatedto dryness to give the title compound (1.4 g) as a colorless foam.

Step B:2-Amino-4-chloro-5-ethyl-7-(β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine

A mixture of the compound from Step A (1.19 g, 2.5 mmol) in MeOH (100mL) and water (50 mL) was stirred with DOWEX H⁺ (to adjust pH of themixture to 5) at room temperature for 2.5 h. The mixture was filteredand the resin thoroughly washed with MeOH. The combined filtrate andwashings were evaporated and the residue coevaporated several times withwater to yield the title compound (0.53 g) as a white solid.

Step C:2-Amino-5-ethyl-7-(β-D-ribofuranosyl)-7H-pyrollo[2,3-d]pyrimidin-4(3H)-one

A mixture of the compound from Step B (104 mg, 0.32 mmol) in 2N aqueousNaOH (10 mL) was stirred at reflux temperature for 15 min. The solutionwas cooled in ice bath, neutralized with 2 N aqueous HCl, and evaporatedto dryness. The residue was suspended in MeOH, mixed with silica gel,and evaporated. The solid residue was placed onto a silica gel column(packed in a solvent mixture of CH₂Cl₂/MeOH: 10/1) which was eluted witha solvent system of CH₂Cl₂MeOH: 10/1 and 5/1. The fractions containingthe product were collected and evaporated to dryness to yield the titlecompound (48 mg) as a white solid.

¹H NMR (CD₃OD): δ 1.22 (t, 3H), 2.69 (q, 2H), 3.69, 3.80 (2m, 2H), 4.00(m, 1H), 4.22 (m, 1H), 4.45 (t, 1H), 5.86 (d, 1H, J=6.0 Hz), 6.60 (d,1H, J=1.2 Hz).

EXAMPLE 102-Amino-7-(3-deoxy-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-one

Step A:2-Amino-7-(2,3-anhydro-β-D-ribofuranosyl)-4-methoxy-7H-pyrrolo[2,3-d]pyrimidine

To a mixture of2-amino-7-(β-D-ribofuranosyl)-4-chloro-7H-pyrrolo[2,3-d]pyrimidine (1.8g, 6.0 mmol) in acetonitrile (80 mL) were added a solution of H₂O/CH₃CN(1:9, 1.08 mL) and then a-acetoxyisobutyryl bromide (3.5 mL, 24 mmol).After 2 h stirring at room temperature, saturated aqueous NaHCO₃ (170mL) was added and the mixture was extracted with EtOAc (300+200 mL). Thecombined organic phase was washed with brine (100 mL), dried (Na₂SO₄)and evaporated to a pale yellow foamy residue. This was suspended inanhydrous MeOH (80 mL) and stirred overnight with 25 mL of DOWEX OH⁻resin (previously washed with anhydrous MeOH). The resin was filtered,washed thoroughly with MeOH and the combined filtrate evaporated to givea pale yellow foam (1.92 g).

Step B:2-Amino-7-(3-deoxy-β-D-ribofuranosyl)-4methoxy-7H-pyrrolo[2,3-d]pyrimidine

A solution of LiEt₃BH/THF (1M, 75 mL, 75 mmol) was added dropwise to acold (ice bath) deoxygenated (Ar, 15 min) solution of the compound fromStep A (1.92 g) under Ar. Stirring at 0° C. was continued for 4 h. Atthis point the reaction mixture was acidified with 5% aqueous aceticacid (110 mL), then purged with Ar for 1 h and and finally evaporated toa solid residue. Purification on a silica gel column using MeOH/CH₂Cl₂as eluent yielded target compound as a colourless foam (1.01 g).

Step C:2-Amino-7-(3-deoxy-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine-4(3H)-one

A mixture of compound from Step B (0.4 g, 1.4 mmol) in 2N aqueous NaOH(40 mL) was stirred at reflux temperature for 3 h. The solution wascooled in ice bath, neutralized with 2 N aqueous HCl and evaporated todryness. The residue was suspended in MeOH, mixed with silica andevaporated. The residue was placed onto a silica gel column which waseluted with CH₂Cl₂/MeOH: 10/1 and 5/1 to give the title compound aswhite solid (0.3 g).

¹H NMR (DMSO-d₆): δ 1.85, 2.12 (2m, 2H), 3.55, 3.46 (2dd, 2H), 4.18 (m,1H); 4.29 (m, 1H), 4.85 (7, 1H), 5.42 (d, 1H) 5.82 (d, 1H, J=2.4 Hz),6.19 (s, 2H), 6.23 (d, 1H, J=3.6 Hz), 6.87 (d, 1H), 10.31 (s, 1H).

EXAMPLE 112-Amino-7-(2-O-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-one

Step A:2-Amino-4-chloro-7-(5-t-butyldimethylsilyl-2,3-O-isopropylidene-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine

HMPT (10.65 ml, 55 mmol) was added portionwise over 30 min. to asolution of5-O-tert-butyldimethylsilyl-2,3-O-isopropylidene-D-ribofuranose (13.3 g,44 mmol), dry THF (135 mL), CCl₄ (5.62 mL, 58 mmol) under N₂ at −76° C.After 30 min., the temp. was raised to −20° C. In a separate flask, asuspension of 2-amino-4-chloro-1H-pyrrolo-[2,3-d]-pyrimidine (15 g, 89mmol) in CH₃CN (900 mL) was treated at 15° C. with 60% NaH (3.60 g., 90mmol.). The reaction was stirred 30 min. whereupon the previous reactionmixture was cannulated with vigorous stirring. The reaction was stirred16 hrs. and then concentrated in vacuo. The resulting semisolid wasadded to ice/water/EtOAc and extracted with EtOAc (3×200 mL), driedNaSO₄, filtered and evaporated. The resulting oil was chromatographed onsilica gel (EtOAc/Hexane 1/1) to afford the product as an oil (9.0 g).

Step B:2-Amino-4-chloro-7-(β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine

A solution of the compound from Step A (5.76 g, 13 mmol) in MeOH/H₂O(1200 mL/600 mL) and Dowex WX8-400 (4.8 g) was stirred 16 hrs. at roomtemperature. The resin was filtered off and the filtrate evaporated toafford the title compound as a white solid; yield 3.47 g.

¹H NMR (DMSO-d₆): δ 3.56 (m, 2H), 3.86 (m, 1H), 4.07 (m, 1H), 4.32 (m,1H), 4.99 (t, 1H), 5.10 (d, 1H), 5.30 (d, 1H), 6.00 (d, 1H), 6.38 (d,1H), 6.71 (s br, 2H), 7.39 (d, 1H).

Step C:2-Amino-4-chloro-7-(2-O-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine

A solution of the compound from Step B1(1.0 g, 3.3 mmol) in dry DMF (100mL) at 15° C. was treated with 60% NaH (0.14 g, 3.5 mmol). After 30min., iodomethane (47 g, 3.3 mmol) was added portionwise to the stirredsolution. The reaction was stirred at room temperature for 16 hrs. andthen evaporated at a temperature below 40° C. The resulting solid waschromatographed on silica gel to afford the product as a white solid;yield 0.81 g.

¹H NMR (DMSO-d₆): δ 3.25 (s, 3H), 3.54 (m, 2H), 3.87 (m, 1H), 4.07 (m,1H), 4.22 (m, 1H), 5.01 (m, 1H), 5.16 (d, 1H), 6.07 (d, 1H), 6.37 (d,1H), 6.70 (s br, 2H), 7.40 (s, 1H). Mass spectrum: m/z 316 (M+1)⁺.

Step D:2-Amino-7-(2-O-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-one

A solution of the compound from Step C (80 mg, 0.25 mmol) in NaOH/H₂O(1.6 g/20 ml) was heated at reflux for 7 hrs., whereupon the solutionwas adjusted with dilute HCl to a pH of 7 and then evaporated.Chromatography of the resulting solid on silica gel with EtOAc/MeOH 8/2afforded the product as a white solid; yield 64 mg.

¹H NMR (DMSO-d₆): δ 3.25 (s, 3H), 3.52 (m, 2H) 3.81 (m, 1H), 4.00 (m,1H), 4.19 (m, 1H), 5.10 (s br, 2H), 5.95 (d, 1H), 6.27 (d, 1H), 6.33 (sbr, 2H), 6.95 (d, 1H), 10.55 (s br, 1H).

EXAMPLE 122-Amino-5-methyl-7-(β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-one

This compound is described in Biochemistry, 33: 2703 (1994) and wassynthesized by the following procedure:

Step A:2-Amino-7-(5-O-tert-butyldimethylsilyl-2,3-O-isopropylidene-β-D-ribofuranosyl)-4-chloro-5-methyl-7H-pyrrolo[2,3-d]pyrimidine

To a stirred suspension of2-amino-4-chloro-5-methyl-1H-pyrrolo[2,3-d]pyrimidine (Liebigs Ann.Chem. 1984, 4, 708) (0.91 g, 5 mmol) in dry MeCN (30 ml) was added NaH(60% in mineral oil; 0.2 g, 5 mmol) and the mixture was stirred at roomtemperature for 0.5 h. A solution of5-O-tert-butyldimethylsilyl-2,3-O-isopropylidene-α-D-ribofuranosylchloride [generated in situ from the corresponding lactol (1.22 g, 4mmol) according to Tetrahedron Lett. 27: 1011 (1986)] in dry THF (6 mL)was added at room temperature, and the mixture was stirred overnight,then evaporated to dryness. The residue was suspended in water (100 mL)and extracted with EtOAc (2×100 mL). The combined organic extracts werewashed with brine, dried (Na₂SO₄) and evaporated. The residue waspurified on a silica gel column using a solvent system of hexanes/EtOAc:7/1 and 5/1. Appropriate fractions were collected and evaporated todryness to give the title compound (0.7 g) as a colorless foam.

Step B:2-Amino-4-chloro-5-methyl-7-(β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine

A mixture of the intermediate from Step A (0.67 g, 1.4 mmol) in MeOH (70ml) and water (35 ml) was stirred with DOWEX H⁺ (to adjust pH of themixture to 5) at room temperature for 4 h. The mixture was filtered andthe resin thoroughly washed with MeOH. The combined filtrate andwashings were evaporated and the residue coevaporated several times withwater to yield the title compound (0.37 g) as a white solid.

Step C:2-Amino-5-methyl-7-(β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-one

A mixture of intermediate from Step B (100 mg, 0.32 mmol) in 2N aqueousNaOH (20 mL) was stirred at reflux temperature for 1.5 h. The solutionwas cooled in ice bath, neutralized with 2 N aqueous HCl and evaporatedto dryness. The residue was suspended in MeOH, mixed with silica gel andevaporated. The solid residue was placed onto a silica gel column(packed in a solvent mixture of CH₂Cl₂/MeOH: 10/1) which was eluted witha solvent system of CH₂Cl₂/MeOH: 10/1 and 5/1. The fractions containingthe product were collected and evaporated to dryness to yield the titlecompound (90 mg) as a white solid.

¹H NMR (DMSO-d₆): δ 2.15 (d, 3H), 3.47, 3.50 (2m, 2H), 3.75 (m, 1H),3.97 (m, 1H), 4.17 (m, 1H), 4.89 (t, 1H), 4.96 (d, 1H), 5.14 (d, 1H),5.80 (d, 1H, J=6.4 Hz), 6.14 (s, 2H), 6.60 (q, 1H, J=1.2 Hz), 10.23 (s,1H).

EXAMPLE 132-Amino-3,4-dihydro-4-oxo-7-(2-O-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine-5-carbonitrile

Step A:2-Amino-4-chloro-7-β-D-ribofuranosyl-7H-pyrrolo[2,3-d]pyrimidine-5-carbonitrile

This intermediate was prepared according to J. Chem. Soc. PerkinTrans. 1. 2375 (1989).

Step B:2-Amino-4-chloro-7-[3,5-O-(1,1,3,3-tetraisopropyldisiloxane-1,3-diyl)-β-D-ribofuranosyl]-7H-pyrrolo[2,3-d]pyrimidine-5-carbonitrile

To a solution of the compound from Step A (1.64 g, 5.00 mmol) in DMF (30mL) was added imidazole (0.681 g, 10.0 mmol). The solution was cooled to0° C. and 1,3-dichloro-1,1,3,3-tetraisopropyldisiloxane (1.58 g, 5.00mmol) was added dropwise. The bath was removed and the solution stirredat room temperature for 30 minutes, evaporated in vacuo to an oil, takenup in ethyl acetate (150 mL) and washed with saturated aqueous sodiumbicarbonate (50 mL) and with water (50 mL). The organic phase was driedover magnesium sulfate, filtered and evaporated in vacuo. The residuewas purified on silica gel using ethyl acetate/hexane (1:2) as eluent.Fractions containing the product were pooled and evaporated in vacuo togive the desired product (2.05 g) as a colorless foam.

¹H NMR (DMSO-d₆): δ 1.03 (m, 28H), 3.92 (m, 1H), 4.01 (m, 1H), 4.12 (m,1H), 4.24 (m, 2H), 5.67 (m, 1H), 5.89 (s, 1H), 7.17 (bs, 2H), 8.04 (s,1H).

Step C:2-Amino-4-chloro-7-[2-O-methyl-β-D-ribofuranosyl]-7H-pyrrolo[2,3-d]pyrimidine-5-carbonitrile

To a pre-cooled solution (0° C.) of the compound from Step B (1.70 g,3.00 mmol) in DMF (30 mL) was added methyl iodide (426 mg, 3.00 mmol)and then NaH (60% in mineral oil) (120 mg, 3.00 mmol). The mixture wasstirred at rt for 30 minutes and then poured into a stirred mixture ofsaturated aqueous ammonium chloride (100 mL) and ethyl acetate (100 mL).The organic phase was washed with water (100 mL), dried over magnesiumsulfate, filtered and evaporated in vacuo. The resulting oily residuewas co-evaporated three times from acetonitrile (10 mL), taken up in THF(50 mL) and tetrabutylammonium fluoride (1.1 mmol/g on silica) (4.45 g,6.00 mmol) was added. The mixture was stirred for 30 minutes, filteredand the filtrate evaporated in vacuo. The crude product was purified onsilica using methanoldichloromethane (7:93) as eluenit. Fractionscontaining the product were pooled and evaporated in vacuo to give thedesired product (359 mg) as a colorless solid.

¹H NMR (DMSO-d₆): δ 3.30 (s, 3H), 3.56 (m, 2H) 3.91 (m, 1H), 4.08 (m,1H), 4.23 (m, 1H), 5.11 (m, 1H), 5.23 (m, 1H), 7.06 (m, 1H), 7.16 (bs,2H), 8.38 (s, 1H).

Step D:2-Amino-3,4-dihydro-4-oxo-7-[2-O-methyl-β-D-ribofuranosyl]-7H-pyrollo[2,3-d]pyrimidine-5-carbonitrile

To a solution of the compound from Step D in DMF (5.0 mL) and dioxane(3.5 mL) was added syn-pyridinealdoxime (336 mg, 2.75 mmol) and thentetramethylguanidine (288 mg, 2.50 mmol). The resulting solution wasstirred overnight at rt, evaporated in vacuo and and co-evaporated threetimes from acetonitrile (20 mL). The oily residue was purified on silicagel using methanol/dichloromethane (7:93) as eluent. Fractionscontaining the product were pooled and evaporated in vacuo to give thedesired product (103 mg) as a colorless solid.

¹H NMR (DMSO-d₆): δ 3.30 (s, 3H), 3.57 (m, 2H), 3.86 (m, 1H), 4.00 (m,1H), 4.21 (m, 1H), 5.07 (m, 1H), 5.17 (m, 1H), 5.94 (m, 1H), 6.56 (bs,2H), 7.93 (s, 1H), 10.82 (bs, 1H).

EXAMPLE 142-Amino-5-methyl-7-(2-O-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-one

Step A:2-Amino-4-chloro-5-methyl-7-(2-O-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]-pyrimidine

Into a solution of the compound from Example 12, Step B (188 mg, 0.6mmol) in anhydrous DMF (6 mL) was added NaH (60% in mineral oil; 26 mg,0.66 mmol). The mixture was stirred at room temperature for 0.5 h andthen cooled. MeI (45 μL) was added at 0° C. and the reaction mixtureallowed to warm to 15° C. in 5 h. Then the mixture was poured intoice-water (20 mL) and extracted with CH₂Cl₂ (100+50 mL). The combinedorganic extracts were washed with water (50 mL), brine (50 mL) and dried(Na₂SO₄). The evaporated residue was purified on a silica gel columnwith a solvent system of CH₂Cl₂/MeOH: 30/1. Appropriate fractions werepooled and evaporated to yield the title compound (50 mg) as a colorlessglass.

Step B:2-Amino-7-(2-O-methyl-β-D-ribofuranosyl)-5-methyl-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-one

A solution of the compound from Step A (50 mg, 0.15 mmol) in 0.5MNaOMe/MeOH (4 mL) was stirred at reflux temperature for 1.5 h. Themixture was cooled, mixed with silica gel and evaporated to dryness. Thesilica gel was loaded onto a silica gel column and eluted with a solventsystem of CH₂Cl₂/MeOH: 30/1. The fractions containing the product werecollected and evaporated to yield2-amino-7-(2-O-methyl-β-D-ribofuranosyl)-4-methoxy-5-methyl-7H-pyrrolo[2,3-d]pyrimidine(40 mg). This was mixed with 2 N aqueous NaOH (4 mL) and stirred atreflux temperature for 10 h. The mixture was cooled in ice bath,neutralized with 2 N aqueous HCl and evaporated. The solid residue wassuspended in MeOH, mixed with silica gel and evaporated. The silica gelwas loaded onto a silica gel column and eluted with a solvent system ofCH₂Cl₂/MeOH: 5/1. Appropriate fractions were pooled and evaporated togive the title compound (40 mg) as a white solid.

¹H NMR (DMSO-d₆): δ 2.18 (s, 3H), 3.26 (s, 3H), 3.45, 3.52 (2m, 2H),3.82 (m, 1H), 3.97 (dd, 1H), 4.20 (m, 1H), 4.99 ((t, 1H), 5.10 (d, 1H),5.94 (d, 1H, J=7.0 Hz), 6.19 (bs, 2H), 6.68 (s, 1H), 10.60 (br, 1H).

EXAMPLE 152-Amino-7-(2-deoxy-2-fluoro-β-D-arabinofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-one

This compound was prepared following the procedures described in J. Med.Chem. 38: 3957 (1995).

EXAMPLE 162-Amino-7-(β-D-arabinofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-one

This compound was prepared following the procedures described in J. Org.Chem. 47: 226 (1982).

EXAMPLE 172-Amino-7-(β-D-arabinofuranosyl)-3,4-dihydro-4-oxo-7H-pyrrolo[2,3-d]pyrimidine-5-carbonitrile

Step A:2-Amino-7-(β-D-arabinofuranosyl)-4-chloro-7H-pyrrolo[2,3-d]pyrimidine-5-carbonitrile

This intermediate was prepared according to J. Chem. Soc. Perkin Trans.1, 2375 (1989).

Step B:2-Amino-7-(β-D-arabinofuranosyl)-3,4-dihydro-4-oxo-7H-pyrrolo[2,3-d]pyrimidine-5-carbonitrile

To a solution of the compound from Step A (163 mg, 0.50 mmol) in DMF(5.0 mL) and dioxane (3.5 mL) was added syn-pyridinealdoxime (336 mg,2.75 mmol) and then tetramethylguanidine (288 mg, 2.50 mmol). Theresulting solution was stirred overnight at rt, evaporated in vacuo andand co-evaporated three times from acetonitrile (20 mL). The oilyresidue was purified on silica using methanol/dichloromethane (1:4) aseluent. Fractions containing the product were pooled and evaporated invacuo to give the desired product (72 mg) as a colorless solid.

¹H NMR (DMSO-d₆): δ 3.60 (m, 2H), 3.73 (m, 1H), 4.01 (m, 2H), 5.06 (m,1H), 5.48 (m, 2H), 6.12 (m, 1H), 6.52 (bs, 2H), 7.70 (s, 1H), 10.75 (bs,1H).

EXAMPLE 182-Amino-5-methyl-7-(β-D-arabinofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-one

Step A2-Amino-7-(2,3,5-tri-O-benzyl-β-D-arabinofuranosyl)-4-chloro-5-methyl-7H-pyrrolo[2,3-d]pyrimidine

To a solution of 1-O-p-nitrobenzyl-D-arabinofuranose (3.81 g, 6.70 mmol)in DCM was bubbled HBr until TLC (hexane/ethylacetate (2:1)) showedcomplete reaction (about 30 min). The reaction mixture was filtered andevaporated in vacuo. The oily residue was taken up in acetonitrile (10mL) and added to a vigorously stirred suspension of2-amino-4-chloro-5-methyl-7H-pyrrolo[2,3-d]pyrimidine (Liebigs Ann.Chem. (1984), 4,708) (1.11 g, 6.00 mmol) KOH (1.12 g, 20.0 mmol) andtris[2-(2-methoxyethoxy)ethyl]amine (0.216 g, 0.67 mmol) in acetonitrile(80 mL). The resulting suspension was stirred at rt for 30 min, filteredand evaporated in vacuo. The crude product was purified on silica usinghexane/ethylacetate (3:1) as the eluent. Fractions containing theproduct were pooled and evaporated in vacuo to give the desired product(1.13 g) as a colorless foam.

Step B:2-Amino-7-β-D-arabinofuranosyl-4-chloro-5-methyl-7H-pyrrolo[2,3-d]pyrimidine

To a precooled (−78° C.) solution of the compound from Step A (0.99 g,1.7 mmol) in dichloromethane (30 mL) was added borontrichloride (1M indichloromethane) (17 mL, 17.0 mmol) over a 10 min. The resultingsolution was stirred at −78° C. for 1 h, allowed to warm to −15° C. andstirred for another 3 h. The reaction was quenched by addition ofmethanol/dichloromethane (1:1) (15 mL), stirred at −15° C. for 30 min,and pH adjusted to 7.0 by addition of NH₄OH. The mixture was evaporatedin vacuo and the resulting oil purified on silica usingmethanol/dichloromethane (1:9) as eluent. Fractions containing theproduct were pooled and evaporated in vacuo to give the desired product(257 mg) as a colorless foam.

Step C:2-Amino-7-(β-D-arabinofuranosyl)-5-methyl-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-one

To the compound from Step B (157 mg, 0.50 mmol) was added NaOH (2M,aqueous) (2 mL). The resulting solution was stirred at reflux for 1 h,cooled and neutralized by addition of HCl (2M, aqueous). The mixture wasevaporated in vacuo and the crude product purified on silica usingmethanol/dichloromethane (2:8) as eluent. Fractions containing theproduct were pooled and evaporated in vacuo to give the desired product(53 mg) as a colorless powder.

¹H NMR (DMSO-d₆): δ 2.13 (d, 3H), 3.58 (m, 2H), 3.71 (m, 1H), 4.00 (m,2H), 5.09 (m, 1H), 6.22 (bs, 2H), 5.50 (m, 2H), 6.12 (m, 1H), 6.64 (s,1H), 10.75 (bs, 1H).

EXAMPLE 192-Amino-7-(3-deoxy-3-fluoro-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-one

A solution1-O-acetyl-2-O-benzyl-5-O-(p-toluoyl)-3-deoxy-3-fluoro-D-ribofuranose(410 mg, 1.01 mmol) (prepared by a modified method described for similarsugar derivatives, Helv. Chim. Acta 82: 2052 (1999) and J. Med.Chem.1991, 34, 2195) in anhydrous CH₂Cl₂ (1.5 mL) was cooled to −15° C.in a dry ice/CH₃CN bath. After cooling the reaction mixture for 10 min.under the argon atmosphere, 33% HBr/AcOH (370 μL, 1.5 equiv.) was addedslowly over 20 min keeping the bath temperature around −15° C. After theaddition was complete, the reaction mixture was stirred at −10° C. for 1hr. The solvent was removed under reduced pressure and the residueazeotroped with anhydrous toluene (5×10 mL). In a separate flask,2-amino-4-chloro-7H-pyrrolo[2,3-d]pyrimidine (210 mg, 1.2 mmol) wassuspended in anhydrous CH₃CN (10 mL) and cooled to −10° C. To this wasadded 60% NaH dispersion in oil (57 mg) in two portions, and thereaction mixture was stirred for 45 min. during which time the soliddissolved and the bath temperature rose to 0° C. The bath was removedand stirring was continued for about 20 additional min. It was cooledback to −10° C. and the bromo sugar, prepared above, was taken up inanhydrous CH₃CN (1.5 mL) and added slowly to the anion of nucleobase .After the addition was complete, the reaction mixture was stirred for anadditional 45 min allowing the temperature of the reaction to rise to 0°C. The bath was removed and the reaction allowed to stir at roomtemperature for 3 hr. Methanol was added carefully to the reactionmixture and the separated solid removed by filtration. The solvent wasremoved under reduced pressure and the residual oil dissolved in EtOAc(50 mL) and washed with water (3×20 mL). The organic layer was driedover Na₂SO₄ and concentrated to give an oil. It was purified by columnchromatography to furnish fully protected2-amino-7-(5-O-(p-toluoyl)-2-O-benzyl-3-deoxy-3-fluoro-β-D-ribofuranosyl)-4-chloro-7H-pyrrolo[2,3-d]pyrimidine(190 mg) as an α/β mixture (1:1). After conversion of 4 chloro to 4-oxoby heating the compound with 2N NaOH/dioxane mixture at 105° C. andafter the usual workup the residue was debenzylated using 20 mol % w/wof 10% Pd/C and ammonium formate in refluxing methanol to give titlecompound after purification by HPLC; yield 10%. ESMS: calcd. forC₁₁H₁₃FN₄O₄ 284.24, found 283.0 (M+1).

EXAMPLE 202-Amino-3,4-dihydro-4-oxo-7-(2-deoxy-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine-5-carbonitrile

This compound was prepared following the procedures described inSynthesis 1327 (1998).

EXAMPLE 216-Amino-1-(β-D-ribofuranosyl)-1H-imidazo[4,5-d]pyridin-4(5H)-one

This compound was prepared following the conditions described in J. Am.Chem. Soc. 97: 2916 (1975).

EXAMPLE 222-Amino-7-(2-O-methyl-β-D-ribofuranosyl)-5H-pyrrolo[3,2-d]pyrimidin-4-(3H)-one

To a suspension of 2-amino-5H-pyrrolo[3,2-d]pyrimidin-4(3H)-one(9-deazaguanine) (0.454 g, 3.0 mmol) (prepared according to J. Org.Chem.1978, 43, 2536) and 2-O-methyl-1,3,5-tri-O-benzoyl-β-D-ribofuranose(1.54 g, 3.2 mmol) in dry nitromethane (23 mL) at 60° C. was addedstannic chloride (0.54 mL, 4.5 mmol). The reaction mixture wasmaintained at this temperature for 0.5 hr., cooled and poured ontoice-cold saturated sodium bicarbonate solution (70 mL). The insolublematerial was filtered through florisil and washed with ethyl acetate(3×50 mL). The filtrate was extracted with ethyl acetate (2×50 mL), andorganic layer was washed with water (2×50 mL), dried over Na₂SO₄ andevaporated to dryness. Chromatography of the resulting foam on silicagel with CH₂Cl₂/MeOH(14:1) afforded the benzoylated product (0.419 g,30% yield). To a suspension of the benzoylated product (0.25 g) in MeOH(2.4 mL) was added t-butylamine (0.52 mL) and stirring at roomtemperature was continued for 24 hrs. followed by addition of moret-butylamine (0.2 mL). The reaction mixture was stirred at ambienttemperature overnight, concentrated in vacuum and the residue waspurified by flash chromatography over silica gel using CH₂Cl₂/MeOH(85:15) as eluent giving the desired compound as a foam (0.80 g).

¹H NMR (200 Mz, DMSO-d₆): δ Hz3.28 (s, 3H), 3.40-3.52 (m, 3H), 3.87-3.90(m, 1H), 4.08-4.09 (m, 1H), 4.67 (d, 1H, J=5.2 Hz), 4.74 (d, 1H, J=7.0Hz), 5.62 and 5.50 (2 bs, 3H), 7.14 (d, 1H, J=2.6 Hz), 10.43 (s, 1H),11.38 (s, 1H); Mass spectrum: calcd. for C₁₂H₁₆N₄O₅: 296.28; found:295.11.

EXAMPLE 236-Amino-1-(3-deoxy-β-D-ribofuranosyl)-1H-imidazo[4,5-c]pyridine-4(5H)-one(3′-deoxy-3-deaza-guanosine)

Step A: β-Deoxy-4-O-p-toluoyl-2-O-acetyl-(β-D-ribofuranosyl acetate

A solution of3-deoxy-4-O-p-toluoyl-1,2-O-isopropylidene-β-D-ribofuranose (NucleosidesNucleotides 1994, 13, 1425 and Nucleosides Nucleotides 1992, 11, 787)(5.85 g, 20 mmol) in 64 mL of 80% acetic acid was stirred at 85° C.overnight. The reaction mixture was concentrated and co-evaporated withtoluene. The residue was dissolved in 90 mL of pyridine. Aceticanhydride (6 mL) was added at 0° C., and the reaction mixture wasstirred at rt for 6 h. After condensation, the residue was dissolved inethyl acetate and washed with aqueous sodium bicarbonate solution, waterand brine. The organic phase was dried and concentrated.

Chromatographic purification on a silica gel column using 3:1 and 2:1hexanes-EtOAc as eluent provided 5.51 g of the title compound as a clearoil.

¹H NMR (CDCl₃): δ 1.98 (s, 3H), 2.09 (s, 3H), 2.15-2.35 (m, 2H), 2.41(s, 3H), 4.27-4.42 (m, 1H), 4.46-4.58 (m, 1H), 4.65-4.80 (m, 1H),5.21-5.28 (m, 1H), 6.20 (s, 1H 7.19-7.31 (m, 2H), 7.90-8.01 (m, 2H).

Step B: Methyl5-cyanomethyl-1-(3-deoxy4-O-p-toluoyl-2-O-acetyl-β-D-ribofuranosyl)-1H-imidazole-4-carboxylate

A mixture of methyl 5(4)-(cyanomethyl)-1H-imidazole-4(5)-carboxylate (J.Am. Chem. Soc. 1976, 98, 1492 and J. Org. Chem. 1963, 28, 3041) (1.41 g,8.53 mmol), 1,1,1,3,3,3-hexamethyldisilazane (20.5 mL) and ammoniumsulfate (41 mg) was refluxed at 125° C. under Ar atmosphere for 18 h.After evaporation, the residue was dissolved in 10 mL of dichloroethane.A solution of the compound from Step A (2.86 g, 8.5 mmol) in 10 mL ofdichloroethane was added followed by addition of SnCl₄ (1.44 mL, 3.20g). The resulted reaction mixture was stirred at rt overnight anddiluted with chloroform. The mixture was washed with aqueous sodiumbicarbonate water and brine. The organic phase was dried andconcentrated. Chromatographic purification of the residue on a silicagel column using 1:1, 1:2, and 1:3 hexanes-EtOAc as eluent provided 2.06g of the title compound as a white foam.

¹H NMR (CDCl₃) δ 2.15 (s, 3H), 2.28-2.40 (m, 2H), 2.38 (s, 3H), 3,87 (s,3H), 4.46 (dd, 2H, J=7.6, 2.0 Hz), 4.50-4.57 (m, 1H), 4.68-4.75 (m, 1H),4.76-4.83 (m, 1H), 5.41 (d, 1H, J=5.6 Hz), 5.91 (s, 1H), 7.24-7.28 (m,2H), 7.80 (s, 1H), 7.82-7.90 (m, 2H); ¹³C NMR (CDCl₃) δ 13.1, 20.7,21.6, 31.5, 51.8, 63.5, 77.9, 79.2, 89.8, 115.1, 126.2, 129.3, 129.5,131.7, 135.1, 144.3, 163.1, 166.1, 170.3.

Step C:6-Amino-1-(3-deoxy-β-D-ribofuranosyl)-1H-imidazo[4,5-c]pyridine-4(5H)-one

A solution of the compound from Step B (2.00 g, 4.53 mmol) in methanol(30 mL) was saturated with ammonia at 0° C. Concentrated ammoniumhydroxide (30 mL) was added and the sealed metal reactor was heated at85° C. for 5 h. After cooling to rt, the reaction mixture wastransferred directly onto a silica gel column. Elution with 4:1, 3:1 and2:1 CHCl₃-MeOH provided 0.79 g of the title compound as a white solid.

¹H NMR (DMSO-d₆): δ 2.41-2.46 (m, 1H), 2.52-2.58 (m, 1H), 3.48-3.55 (m,1H), 3.60-3.70 (m, 1H), 4.27-4.36 (m, 2H), 4.97 (t, 1H, J=5.6 Hz), 5.44(s, 1H), 5.47 (s, 1H), 5.60 (s, 2H), 5.66, (d, 1H, J=4.4 Hz), 7.90 (s,1H), 10.33 (s, 1H); ¹³C NMR (DMSO d₆) δ 34.1, 62.4, 70.4, 74.7, 80.4,91.6, 123.0, 136.3, 141.9, 147.6, 156.5.

EXAMPLE 246-Amino-1-(3-deoxy-3-fluoro-β-D-ribofuranosyl)-1H-imidazo[4,5-c]pyridin-4(3H)-one

This compound was prepared in a manner similar to the preparation of2-amino-7-(3-deoxy-3-fluoro-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-one(Example 23).

EXAMPLE 25 1-(β-D-Ribofuranosyl)-1H-pyrazolo[3,4-d]pyrimidin-4(3H)-one(Allopurinol riboside)

This compound was obtained from commercial sources.

EXAMPLE 26 9-(β-D-Arabinofuranosyl)-9H-purin-6(1H)-one

This compound was prepared following the conditions described in J. Med.Chem. 18: 721(1975).

EXAMPLE 272-Amino-7-(2-O-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-thione

A solution of the compound from Example 11, Step C (1.5 g, 5 mmol),thiourea (0.4 g, 5.2 mmol.) in abs. EtOH was refluxed for 16 hrs. Thesolution was evaporated and the resulting oil chromatographed on silicagel (EtOAc/MeOH: 9/1) to afford the desired product as a foam.

¹H NMR (DMSO-d₆): δ 3.30 (s, 3H), 5.00-5.06 (t, 1H), 5.19 (d, 1H), 5.95(d, 1H), 6.43 (d, 1H), (d, 1H).

EXAMPLE 28 2-Amino-7-(β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine

This compound was obtained from commercial sources.

EXAMPLE 292-Amino-4-chloro-7-(2-O-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-5-carbonitrile

This compound was prepared as described in Example 13, Steps A-C.

EXAMPLE 302-Amino-4-chloro-5-ethyl-7-(2-O-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine

Step A:2-Amino-4-chloro-5-ethyl-7-[3,5-O-(tetraisopropyldisiloxane-1,3-diyl)-β-D-ribofuranosyl]-7H-pyrrolo[2,3-d]pyrimidine

To a solution of2-amino-4-chloro-5-ethyl-7-(β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine(0.300 g, 0.913 mmol) in pyridine, (8 mL) was added1,3-dichloro-1,1,3,3-tetraisopropyldisiloxane (0.317 g, 1.003 mmol)dropwise. The solution stirred at rt overnight, evaporated in vacuo toan oil, and evaporated repeatedly from acetonitrile. The crude productwas purified on silica using 5% methanol in dichloromethane as eluent.Fractions containing the product were pooled and evaporated in vacuo togive the desired product (254 mg) as a colorless solid.

Step B:2-Amino-4-chloro-5-ethyl-7-(2-O-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine

To a pre-cooled solution (0° C.) of the compound from step A (192 mg,0.337 mmol) in DMF (3 mL) was added methyl iodide (45.4 mg, 0.320 mmol)and then NaH (60% in mineral oil) (8.10 mg, 0.320 mmol). The mixture wasstirred at rt for 45 minutes and then poured into a stirred mixture ofsaturated aqueous ammonium chloride (10 mL) and ethyl acetate (10 mL).The organic phase phase was washed with brine (10 mL) and dried overMgSO₄ and evaporated in vacuo. The resulting oily residue was taken upin THF (5 mL) and tetrabutylammonium fluoride (1.1 mmol/g on silica)(0.529 g, 0.582 mmol) was added. The mixture was stirred for 30 minutes,filtered and the filtrate evaporated in vacuo. The crude product waspurified on silica using 10% methanol in dichloromethane as eluent.Fractions containing the product were pooled and evaporated in vacuo togive the desired product (66 mg) as a colorless solid.

¹H NMR (DMSO-d₆): δ 1.15 (t, 3H), 2.65 (q, 2H), 3.20 (s, 3H), 3.51 (m,2H), 3.84 (m, 1H), 4.04 (m, 1H), 4.21 (m, 1H), 4.99 (m, 2H), 5.15 (m,2H), 6.07 (m, 2H), 6.62 (s br, 2H), 7.06 (s, 2H).

EXAMPLE 312-Amino-4-chloro-5-methyl-7-(2-O-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine

This compound was prepared as described in Example 14, Step A.

¹H NMR (CD₃OD): δ 2.33 (s, 3H), 3.39 (s, 1H), 3.72, 3.83 (2dd, 2H), 4.03(m, 1H), 4.17 (t, 1H), 4.39 (dd, 1H), 5.98 (d, 1H, J=5.9 Hz), 6.7 (bs,2H), 7.01 (s, 1H).

EXAMPLE 322-Amino-4-chloro-7-(2-O-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine

This compound was synthesized as described in Example 11, Steps A-C.

EXAMPLE 332-Amino-4-chloro-7-(β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine

This compound was prepared following the procedures described in Helv.Chim. Acta 73: 1879 (1990).

EXAMPLE 342-Amino-4-chloro-5-methyl-7-(β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine

The compound was prepared as described in Example 12, Steps A-B.

¹H NMR (DMSO-d₆): δ 2.29 (s, 3H), 3.54 (m, 2H), 3.84 (m, 1H), 4.04 (dd,1H, J₁=3.0, J₂=4.9 Hz), 4.80-5.50 (bs, 3H), 4.28 (t, 1H), 5.98 (d, 1H,J=6.5 Hz), 6.7 (bs, 2H), 7.13 (s, 1H).

EXAMPLE 352-Amino-4-chloro-5-ethyl-7-(β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine

This compound was prepared as described in Example 9, Steps A-B.

¹H NMR (DMSO-d₆): δ 2.00 (t, 3H), 2.69 (q, 2H), 3.48 (dd, 1 H, J₁=4.2Hz, J₂=11.8 Hz), 3.56 (dd, 1H, J₁=4.3 Hz, J₂=11.8 Hz), 3.80 (m, 1H),4.02 (dd, 1H, J₁=3.1 Hz, J₂=5.0 Hz), 4.62 (t, 1H), 5.0 (bs, 2H), 5.2(bs, 1H), 5.60 (d, 1H, J=6.4 Hz), 6.61 (bs, 2H), 7.09 (s, 1H).

EXAMPLE 36 2-Amino-6-chloro-9-(β-D-ribofuranosyl)-9H-purine

This compound was obtained from commercial sources.

EXAMPLE 372-Amino-4-chloro-7-(β-D-ribofuranosyl)-7H-pyrollo[2,3-d]pyrimidine-5-carbonitrile

This compound was prepared following the procedures described in J.Chem. Soc. Perkin Trans. 1, 2375 (1989).

EXAMPLE 382-Amino-4-chloro-7-(2-deoxy-2-fluoro-β-D-arabinofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine

This compound was prepared following the procedures described in J. Med.Chem. 38: 3957 (1995).

EXAMPLE 392-Amino-4-chloro-5-methyl-7-(β-D-arabinofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine

The compound was prepared as described in Example 18, Steps A-B.

¹H NMR (DMSO-d₆): δ 2.24 (s, 3H), 3.60 (m, 3H), 3.98 (m, 2H), 4.98 (m,1H), 5.43 (bs, 2H), 6.25 (s, 1H), 6.57 (bs, 2H), 7.01 (s, 1H).

EXAMPLE 40 2′-O-Methylcytidine

This compound was obtained from commercial sources.

EXAMPLE 41 3′-Deoxy-3′-methylcytidine

This compound was prepared following the procedures described in U.S.Pat. No. 3,654,262 (1972), which is incorporated by reference herein inits entirety.

EXAMPLE 42 3′-Deoxycytidine

This compound was obtained from commercial sources.

EXAMPLE 43 3′-Deoxy-3′-fluorocytidine

This compound was prepared following the procedures described in J. Med.Chem. 34: 2195 (1991).

EXAMPLE 44 1-(β-D-Arabinofuranosyl)-1H-cytosine

This compound was obtained from commercial sources.

EXAMPLE 45 2′-Amino-2′-deoxycytidine

This compound was obtained from commercial sources.

EXAMPLE 46 3′-Deoxy-3′-methyluridine

This compound was prepared following procedures described in U.S Pat.No. 3,654,262, which is incorporated by reference herein in itsentirety.

EXAMPLE 47 3′-Deoxy-3′-fluorouridine

This compound was prepared following procedures described in J. Med.Chem. 34: 2195 (1991) and FEBS Lett. 250: 139 (1989).

EXAMPLE 48 3′-Deoxy-5-methyluridine

This compound was obtained from commercial sources.

EXAMPLE 49 3′-Deoxy-2′-O-(2-methoxyethyl)-3′-methyl-5-methyluridine

Step A:5′-O-(tert-butyldiphenylsilyl)-3′-O-(3-tert-butylphenoxythiocarbonyl)-2′-O-(2-methoxyethyl)-5-methyluridine

This compound was synthesized by the reaction of the corresponding5′-protected-2′-substituted-5-methyluridine with 3′-t-butylphenoxychlorothionoformate following the similar procedure for the preparationof 3′-phenoxythiocarbonyl-2′-deoxy derivative (Synthesis 1994, 1163).

Step B:5′-O-(tert-Butyldiphenylsilyl)-3′-deoxy-2′-O-(2-methoxyethyl)-3′-(2-phenylethenyl)-5-methyluridine

To a solution of5′-O-(tert-butyldiphenylsilyl)-3′-O-(3-tert-butylphenoxythiocarbonyl)-2′-O-(2-methoxyethyl)-5-methyluridine(15.0 g, 20.0 mmol) in 150 mL of benzene was added PhCH═CHSnBu₃ (18.7 g,50 mmol). The resulting solution was degassed three times with argon atrt and 45° C. After AIBN (1.0 g, 6.1 mmol) was added, the resultingsolution was refluxed for 2 h. Another portion of AIBN (1.0 g, 6.1 mmol)was added after cooling to about 40° C. and refluxed for 2 h. Thisprocedure was repeated until the starting material disappeared. Thesolvent was evaporated and the residue was purified by flashchromatography on a silica gel column using 10:1 and 5:1 hexanes-EtOAcas eluent to give 1.74 g of5′-O-(tert-butyldiphenylsilyl)-3′-deoxy-2′-O-(2-methoxyethyl)-3′-(2-phenylethenyl)5-methyluridineas a white foam.

¹H NMR (CDCl₃): δ 1.13, (s, 9H), 1.43 (s, 3H), 3.18-3.30 (m, 1H), 3.37(s, 3H), 3.58-3.62 (m, 2H), 3.79-3.80 (m, 2H), 4.06-4.37 (m, 4H), 4.95(s, 1H), 6.25-6.40 (m, 1H), 6.62 (d, 1H, J=16 Hz), 7.27-7.71 (m, 16H),9.21 (s, 1H); ¹³C NMR (CDCl₃) δ 11.9, 19.6, 27.2, 45.3, 59.0, 62.1,70.2, 72.0, 84.6, 87.1, 90.2, 110.4, 122.8, 126.4, 127.8, 128.0, 128.3,128.6, 130.0, 132.7, 133.5, 134.7, 135.3, 135.4, 136.9, 150.3, 154.1;HRMS (FAB) m/z 641.302 (M+H)⁺ (C₃₇H₄₅N₂O₆Si requires 641.304).

Step C: 5′-O-(tert-Butyldiphenylsilyl)-3′-deoxy-3′-(hydroxymethyl-2′-O-(2-methoxyethyl)-5-methyluridine

To a solution of5′-O-(tert-butyldiphenylsilyl)-3′-deoxy-2′-O-(2-methoxyethyl)-3′-(2-phenylethenyl)-5-methyluridine.(5.0 g, 7.8 mmol) and N-methylmorpholine N-oxide (NMO) (1.47 g, 12.5mmol) in 150 mL of dioxane was added a catalytic amount of osmiumtetraoxide (4% aqueous solution, 2.12 mL, 85 mg, 0.33 mmol). The flaskwas covered by aluminum foil and the reaction mixture was stirred at rtovernight. A solution of NaIO₄ (5.35 g, 25 mmol) in 5 mL of water wasadded to the above stirred reaction mixture. The resulting reactionmixture was stirred for 1 h at 0° C. and 2 h at rt, followed by additionof 10 mL of ethyl acetate. The mixture was filtered through a celite padand washed with ethyl acetate. The filtrate was washed 3 times with 10%aqueous Na₂S₂O₃ solution until the color of aqueous phase disappeared.The organic phase was further washed with water and brine, dried(Na₂SO₄) and concentrated. The aldehyde thus obtained was dissolved in130 mL of ethanol-water (4:1, v/v). Sodium borohydride (NaBH₄) (1.58 g,40 mmol) was added in portions at 0° C. The resulting reaction mixturewas stirred at rt for 2 h and then treated with 200 g of ice water. Themixture was extracted with ethyl acetate. The organic phase was washedwith water and brine, dried (Na₂SO₄) and concentrated. The resultedresidue was purified by flash chromatography on a silica gel columnusing 2:1, 1:1 and 1:2 hexanes-EtOAc as eluents to give 1.6 g of5′-O-(tert-butyldiphenylsilyl)-3′-deoxy-3′-(hydroxymethyl)-2′-O-(2-methoxyethyl)-5-methyluridineas a white foam.

¹H NMR (CDCl₃): δ 1.09 (s, 9H), 1.50 (s, 3H), 2.25 (bs, 1H), 2.52-2.78(m, 1H), 3.38 (s, 3H), 3.52-4.25 (m, 10H), 5.86 (s, 1H), 7.38-7.70 (m,11H), 9.95 (bs, 1H); ¹³C NMR (CDCl₃): δ 12.1, 19.5, 27.1, 43.1, 58.2,58.8, 63.1, 69.5, 71.6, 82.3, 86.1, 89.8, 110.5, 128.0, 130.2, 132.5,133.2, 135.1, 135.3, 136.5, 150.5, 164.4; HRMS (FAB) m/z 569.268 (M+H)⁺(C₃₀H₄₁N₂O₇Si requires 569.268).

Step D: 5′-O-(tert-Butyldiphenylsilyl-3′-deoxy-3′-(iodomethyl)-2′-O-(2-methoxyethyl)-5-methyluridine

To a solution of5′-O-(tert-butyldiphenylsilyl)-3′-deoxy-3′-(hydroxymethyl)-2′-O-(2-methoxyethyl)-5-methyluridine (1.34 g, 2.35 mmol) in 25 mL of anhydrous DMP understirring was added sequentially at 0° C. 2,6-lutidine (0.55 mL, 0.51 g,4.7 mmol, 2.0 equiv) and methyl triphenoxy-phosphonium iodide (1.28 g,2.83 mmol). The resulting reaction mixture was stirred at 0° C. for 1 hand at rt for 2 h. The reaction mixture was diluted with 10 mL of ethylacetate and washed twice with 0.1 N Na₂S₂O₃ aqueous solution to removeiodine. The organic phase was further washed with aqueous NaHCO₃solution, water, and brine. The aqueous phases were back extracted withethyl acetate. The combined organic phases were dried (Na₂SO₄) andconcentrated. The resulting residue was purified by flash chromatographyon a silica gel column using 5:1, 3:1 and then 1:1 hexanes-EtOAc toprovide 1.24 g of5′-O-(tert-butyldiphenylsilyl)-3′-deoxy-3′-(iodomethyl)-2′-O-(2-methoxyethyl)-5-methyluridineas a white foam.

¹H NMR (CDCl₃): δ 1.13 (s, 9H), 1.62 (s, 3H), 2.64-2.85 (m, 2H),3.20-3.35 (m, 1H), 3.38 (s, 3H), 3.50-4.25 (m, 8H), 5.91 (s, 1H),7.32-7.50 (m, 6H), 7.60 (s, 1H), 7.62-7.78 (m, 4H), 10.46 (s, 1H); ¹³CNMR (CDCl₃): δ 12.4, 19.5, 27.2, 45.0, 58.0, 62.5, 70.3, 71.9, 83.3,85.6, 88.9, 110.5, 128.1, 128.2, 130.1, 130.3, 132.4, 132.9, 135.0,135.4, 135.6, 150.7, 164.7; HRMS (FAB) m/z 679.172 (M+H)⁺ (C₃₀H₄₀IN₂O₆Sirequires 679.170).

Step E: 3′-Deoxy-3′-tiodomethyl)-2′-O-(2-methoxyethyl)-5-methyluridine

A solution of5′-O-(tert-butyldiphenylsilyl)-3′-deoxy-3′-(iodomethyl)-2′-O-(2-methoxyethyl)-5-methyluridine(1.12 g, 1.65 mmol) and triethylamine trihydrofluoride (1.1 mL, 1.1 g,6.7 mmol) in 20 mL of THF was stirred at rt for 24 h. The reactionmixture was diluted with 50 mL of ethyl acetate and washed with waterand brine. The organic phase was dried (Na₂SO₄) and concentrated. Theresidue was purified by flash chromatography on a silica gel column.Gradient elution with 2:1, 1:2 and then 1:3 hexanes-EtOAc provided 504mg of the title compound as a white foam.

¹H NMR (CD₃OD): δ 1.87 (s, 3H), 2.47-2.75 (m, 1H), 3.18-3.37 (m, 2H),3.40 (s, 3H), 3.59-3.70 (m, 2H), 3.71-3.90 (m, 2H), 3.92-4.17 (m, 4H),5.87 (s, 1H), 8.17 (s, 1H); ¹³C NMR (CD₃OD): δ 12.5, 45.2, 59.2, 60.9,71.0, 72.9, 85.4, 87.3, 89.7, 110.5, 138.0, 152.1, 166.6; HRMS (FAB) m/z441.053 (M+H)⁺ (C₁₄H₂₂IN₂O₆ requires 441.052).

Step F:3′-Deoxy-5′-O-(4-methoxytrityl)-3′-(iodomethyl)-2′-O-(2-methoxyethyl)-5-methyluridine

A mixture of3′-deoxy-3′-(iodomethyl)-2′-O-(2-methoxyethyl)-5-methyluridine (472 mg,1.1 mmol), diisopropylethylamine (0.79 mL, 0.586 g, 4.5 mmol), andp-anisyl chlorodiphenyl methane (4′-methoxytrityl chloride, MMT-Cl)(1.32 g, 4.27 mmol) in 6 mL of ethyl acetate and 4 mL of THF was stirredat rt for 48 h. The reaction mixture was diluted with ethyl acetate andwashed with water, followed by brine. The organic phase was dried(Na₂SO₄) and concentrated. The crude product was purified by flashchromatography on a silica gel column. Gradient elution with 3:1, 2:1,1:1, and then 1:3 hexanes-EtOAc provided 690 mg of the title compound asa white foam.

¹H NMR (CDCl₃): δ 1.46 (s, 3H), 2.70-2.89 (m, 2H), 3.19-3.31 (m, 2H),3.39 (s, 3H), 3.58-3.70 (m, 3H), 3.80 (s, 3H), 3.80-3.94 (m, 1H),4.05-4.25 (m, 3H), 5.89 (s, 1H), 6.85 (s, 1H), 6.89 (s, 1H), 7.24-7.48(m, 12H), 7.78 (s, 1H), 9.69 (s, 1H); ¹³C NMR (CDCl₃): δ 12.3, 45.3,55.3, 58.9, 61.6, 70.2, 71.9, 82.6, 85.6, 87.1, 89.1, 110.5, 113.4,127.4, 128.2, 128.4, 130.5, 134.7, 135.3, 143.6, 143.7, 150.5, 158.9,164.6. HRMS (FAB) m/z 735.155 (M+Na)⁺ (C₃₄H₃₇IN₂O₇Na requires 735.154).

Step G:3′-Deoxy-5′-O-(4-methoxytrityl)-3′-methyl-2′-O-(2-methoxyethyl)-5-methyluridine

A mixture of ammonium phosphinate (410 mg, 5.1 mmol) and1,1,1,3,3,3-hexamethyldisilazane (1.18 mL, 0.90 g, 5.59 mmol) was heatedat 100-110° C. for 2 h under nitrogen atmosphere with condenser. Theintermediate BTSP(bis[trimethylsilyl]phosphinate) was cooled to 0° C.and 5 mL of dichloromethane was injected. To this mixture was injected asolution of3′-deoxy-5′-O-(4-methoxytrityl)-3′-(iodomethyl)-2′-O-(2-methoxyethyl)-5-methyluridine(0.78 g, 1.1 mmol) and diisopropylethylamine (0.39 mL, 287 mg, 2.23mmol) in 7 mL of dichloromethane. After the reaction mixture was stirredat rt overnight, a mixture of THF-MeOH-NEt₃ (3/6/0.3 mL) was added andcontinued to stir for 1 h. The reaction mixture was filtered through apad of celite and washed with dichloromethane. The solvent wasevaporated and the residue was purified by flash chromatography on asilica gel column using 2:1, 1:1, and then 1:2 hexanes-EtOAc as eluentproviding 380 mg of the title compound.

¹H NMR (CDCl₃): δ 0.97 (d, 3H, J=6.8 Hz), 1.41 (s, 3H), 2.35-2.55 (m,1H), 3.27 (dd, 1H, J=11.0, 3.0 Hz), 3.37 (s, 3H), 3.54-3.68 (m, 3H),3.79 (s, 3H), 3.75-3.87 (m, 1H), 3.94 (d, 1H, J=5.0 Hz), 4.03-4.16 (m,2H), 5.84 (s, 1H), 6.83 (s, 1H), 6.87 (s, 1H), 7.20-7.37 (m, 8H),7.39-7.50 (m, 4H), 7.86 (s, 1H), 9.50 (s, 1H; ¹³C NMR (CDCl₃): δ 8.7,12.1, 35.6, 55.3, 59.0, 61.7, 69.8,72.1, 85.4, 86.4, 86.7, 89.8, 110.0,113.3, 127.2, 128.0, 128.4, 130.4, 135.0, 135.7, 143.9, 150.5, 158.8,164.6. HRMS (FAB) m/z 609.256 (M+Na)⁺ (C₃₄H₃₈N₂O₇Na requires 609.257).

Step H: 3′-Deoxy-3′-methyl-2′-O-(2-methoxyethyl)-5-methyluridine

Trifluoroacetic acid (1.5 mL) was added dropwise to a stirred solutionof3′-deoxy-5′-O-(4-methoxytrityl)-3′-methyl-2′-O-(2-methoxyethyl)-5-methyluridine(370 mg, 0.63 mmol) in 50 mL of chloroform at 0° C. The mixture wasstirred at rt for 30 min, concentrated, and then dissolved in ethylacetate. The solution was washed with dilute sodium bicarbonate andbrine. The organic phase was dried (Na₂SO₄) and concentrated. Theresulting residue was purified by flash chromatography on a silica gelcolumn. Elution with 1:1, 1:3 and then 0:1 hexanes-EtOAc provided 170 mgof the title compound as a white foam.

¹H NMR (CDCl₃): δ 1.03 (d, 3H, J=6.8 Hz), 1.83 (s, 3H) 2.20-2.40 (m,1H), 3.10-3.28 (m, 1H), 3.35 (s, 3H), 3.50-4.15 (m, 10H), 5.81 (s, 1H),7.89 (s, 1H), 9.77 (s, 1H); ¹³C NMR (CDCl₃): δ 8.9 12.4, 34.7, 59.0,60.6, 69.7,72.0, 86.3, 89.8, 109.7, 136.9, 150.4, 164.7. HRMS (FAB) m/z315.154 (M+H)⁺ (C₁₄H₂₃N₂O₆ requires 315.155).

EXAMPLE 50 2′-Amino-2′-deoxyuridine

This compound was prepared following the procedures described in J. Org.Chem.61: 781 (1996).

EXAMPLE 51 3′-Deoxyuridine

This compound was obtained from commercial sources.

EXAMPLE 52 2′-C-Methyladenosine

This compound was prepared following the conditions described in J.Med.Chem. 41: 1708 (1998).

EXAMPLE 53 3′-Deoxyadenosine (Cordycepin)

This compound was obtained from commercial sources.

EXAMPLE 54 3′-Amino-3′-deoxyadenosine

This compound was prepared following the conditions described inTetrahedron Lett. 30: 2329 (1989).

EXAMPLE 55 8-Bromoadenosine

This compound was obtained from commercial sources.

EXAMPLE 56 2′-O-Methyladenosine

This compound was obtained from commercial sources.

EXAMPLE 57 3′-Deoxy-3′-fluoroadenosine

This compound was prepared following the procedures described in J. Med.Chem. 34: 2195 (1991).

EXAMPLE 58 6-Methyl-9-(β-D-ribofuranosyl)-9H-purine

This compound was prepared following the procedures described inNucleosides, Nucleotides, Nucleic Acids 19: 1123 (2000).

EXAMPLE 59 2′,3′,5′-tri-O-acetyl-8-methylsulfonyladenosine

EXAMPLE 601-Methyl-9-[2,3,5-tri-O-(p-toluoyl)-β-D-ribofuranosyl]-9H-purine-6(1H)-thione

EXAMPLE 614-Amino-7-(2-C-methyl-β-D-arabinofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine

To chromium trioxide (1.57 g, 1.57 mmol) in dichloromethane (DCM) (10mL) at 0° C. was added acetic anhydride (145 mg, 1.41 mmol) and thenpyridine (245 mg, 3.10 mmol). The mixture was stirred for 15 min, then asolution of7-[3,5-O-[1,1,3,3-tetrakis(1-methylethyl)-1,3-disiloxanediyl]-β-D-ribofuranosyl]-7H-pyrrolo[2,3-d]pyrimidin-4-amine[for preparation, see J. Am. Chem. Soc. 105: 4059 (1983)] (508 mg, 1.00mmol) in DCM (3 mL) was added. The resulting solution was stirred for 2h and then poured into ethyl acetate (10 mL), and subsequently filteredthrough silica gel using ethyl acetate as the eluent. The combinedfiltrates were evaporated in vacuo, taken up in diethyl ether/TBF (1:1)(20 mL), cooled to −78° C. and methylmagnesium bromide (3M, in TEF)(3.30 mL, 10 mmol) was added dropwise. The mixture was stirred at −78°C. for 10 min, then allowed to come to room temperature (rt) andquenched by addition of saturated aqueous ammonium chloride (10 mL) andextracted with DCM (20 mL). The organic phase was evaporated in vacuoand the crude product purified on silica gel using 5% methanol indichloromethane as eluent. Fractions containing the product were pooledand evaporated in vacuo. The resulting oil was taken up in THF (5 mL)and tetrabutylammonium fluoride (TBAF) on silica (1.1 mmol/g on silica)(156 mg) was added. The mixture was stirred at rt for 30 min, filtered,and evaporated in vacuo. The crude product was purified on silica gelusing 10% methanol in dichloromethane as eluent. Fractions containingthe product were pooled and evaporated in vacuo to give the desiredcompound (49 mg) as a colorless solid.

¹H NMR (DMSO-d₆): δ 1.08 (s, 3H), 3.67 (m, 2H), 3.74 (m, 1H), 3.83 (m,1H), 5.19 (m, 1H), 5.23 (m, 1H), 5.48 (m, 1H), 6.08 (1H, s), 6.50 (m,1H), 6.93 (bs, 2H), 7.33 (m, 1H), 8.02 (s, 1H).

EXAMPLE 624-Amino-7-(2-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine

Step A: 3,5-Bis-O-(2,4-dichlorophenylmethyl)-1-O-methyl-α-D-ribofuranose

A mixture of2-O-acetyl-3,5-bis-O-(2,4-dichlorophenylmethyl)-1-O-methyl-α-D-ribofuranose[for preparation, see: Helv. Chim. Acta 78: 486 (1995)] (52.4 g, 0.10mol) in methanolic K₂CO₃ (500 mL, saturated at room temperature) wasstirred at room temperature for 45 min. and then concentrated underreduced pressure. The oily residue was suspended in CH₂Cl₂ (500 mL),washed with water (300 mL+5×200 mL) and brine (200 mL), dried (Na₂SO₄),filtered, and concentrated to give the title compound (49.0 g) ascolorless oil, which was used without further purification in Step Bbelow.

¹HMR (DMSO-d₆): δ 3.28 (s, 3H, OCH₃), 3.53 (d, 2H, J_(5,4)=4.5 Hz, H-5a,H-5b), 3.72 (dd, 1H, J_(3,4)=3.6 Hz, J_(3,2)=6.6 Hz, H-3), 3.99 (ddd,1H, J_(2,1)=4.5 Hz, J_(2,OH-2)=9.6 Hz, H-2), 4.07 (m, 1H, H-4), 4.50 (s,2H, CH₂Ph), 4.52, 4.60 (2d, 2H, J_(gem)=13.6 Hz, CH₂Ph), 4.54 (d, 1H,OH-2), 4.75 (d, 1H, H-1), 7.32-7.45, 7.52-7.57 (2m, 10H, 2Ph).

¹³C NMR (DMSO-d₆) δ 55.40, 69.05, 69.74, 71.29, 72.02, 78.41, 81.45,103.44, 127.83, 127.95, 129.05, 129.28, 131.27, 131.30, 133.22, 133.26,133.55, 133.67, 135.45, 135.92.

Step B:3,5-Bis-O-(2,4-dichlorophenylmethyl)-1-O-methyl-α-D-erythro-pentofuranos-2-ulose

To an ice-cold suspension of Dess-Martin periodinane (50.0 g, 118 mmol)in anhydrous CH₂Cl₂ (350 mL) under argon (Ar) was added a solution ofthe compound from Step A (36.2 g, 75 mmol) in anhydrous CH₂Cl₂ (200 mL)dropwise over 0.5 h. The reaction mixture was stirred at 0° C. for 0.5 hand then at room temperature for 3 days. The mixture was diluted withanhydrous Et₂O (600 mL) and poured into an ice-cold mixture ofNa₂S₂O₃.5H₂O (180 g) in saturated aqueous NaHCO₃ (1400 mL). The layerswere separated, and the organic layer was washed with saturated aqueousNaHCO₃ (600 mL), water (800 mL) and brine (600 mL), dried (MgSO₄),filtered and evaporated to give the title compound (34.2 g) as acolorless oil, which was used without further purification in Step Cbelow.

¹H NMR (CDCl₃) δ 3.50 (s, 3H, OCH₃), 3.79 (dd, 1H, J_(5a,5b)=11.3 Hz,J_(5a,4)=3.5 Hz, H-5a), 3.94 (dd, 1H, J_(5b,4)=2.3 Hz, H-5b), 4.20 (dd,1H, J_(3,1)=1.3 Hz, J_(3,4)=8.4 Hz, H-3), 4.37 (ddd, 1H, H-4), 4.58,4.69 (2d, 2H, J_(gem)=13.0 Hz, CH₂Ph), 4.87 (d, 1H, H-1), 4.78, 5.03(2d, 2H, J_(gem)=12.5 Hz, CH₂Ph), 7.19-7.26, 7.31-7.42 (2m, 10H, 2Ph).

¹³C NMR (DMSO-d₆) δ 55.72, 69.41, 69.81, 69.98, 77.49, 78.00, 98.54,127.99, 128.06, 129.33, 129.38, 131.36, 131.72, 133.61, 133.63, 133.85,133.97, 134.72, 135.32, 208.21.

Step C:3,5-Bis-O-(2,4-dichlorophenylmethyl)-2-C-methyl-1-O-methyl-α-D-ribofuranose

To a solution of MeMgBr in anhydrous Et₂O (0.48 M, 300 mL) at −55° C.was added dropwise a solution of the compound from Step B (17.40 g, 36.2mmol) in anhydrous Et₂O (125 mL). The reaction mixture was allowed towarm to −30° C. and stirred for 7 h at −30° C. to −15° C., then pouredinto ice-cold water (500 mL) and the mixture vigorously stirred at roomtemperature for 0.5 h. The mixture was filtered through a Celite pad(10×5 cm) which was thoroughly washed with Et₂O. The organic layer wasdried (NgSO₄), filtered and concentrated. The residue was dissolved inhexanes (−30 mL), applied onto a silica gel column (10×7 cm, prepackedin hexanes) and eluted with hexanes and hexanes/EtOAc (9/1) to give thetitle compound (16.7 g) as a colorless syrup.

¹H NMR (CDCl₃): δ 1.36 (d, 3H, J_(Me,OH)=0.9 Hz, 2C-Me), 3.33 (q, 1H,OH), 3.41 (d, 1H, J_(3,4)=3.3 Hz), 3.46 (s, 3H, OCH₃), 3.66 (d, 2H,J_(5,4)=3.7 Hz, H-5a, H-5b), 4.18 (apparent q, 1H, H-4), 4.52 (s, 1H,H-1), 4.60 (s, 2H, CH₂Ph), 4.63, 4.81 (2d, 2H, J_(gem)=13.2 Hz, CH₂Ph),7.19-7.26, 7.34-7.43 (2m, 10H, 2Ph).

¹³C NMR (CDCl₃): δ 24.88, 55.45, 69.95, 70.24, 70.88, 77.06, 82.18,83.01, 107.63, 127.32, 129.36, 130.01, 130.32, 133.68, 133.78, 134.13,134.18, 134.45, 134.58.

Step D:4-Chloro-7-[3,5-bis-O-(2,4-dichlorophenylmethyl)-2-C-methyl-β-D-ribofuranosyl]-7H-pyrrolo[2,3-d]pyrimidine

To a solution of the compound from Step C (9.42 g, 19 mmol) in anhydrousdichloromethane (285 mL) at 0° C. was added HBr (5.7 M in acetic acid,20 mL, 114 mmol) dropwise. The resulting solution was stirred at 0° C.for 1 h and then at room temperature for 3 h, evaporated in vacuo andco-evaporated with anhydrous toluene (3×40 mL). The oily residue wasdissolved in anhydrous acetonitrile (50 mL) and added to a solution ofsodium salt of 4-chloro-1H-pyrrolo[2,3-d]pyrimidine [for preparation,see J. Chem. Soc., 131 (1960)] in acetonitrile [generated in situ from4-chloro-1H-pyrrolo[2,3-d]pyrimidine (8.76 g, 57 mmol) in anhydrousacetonitrile (1000 mL), and NaH (60% in mineral oil, 2.28 g, 57 mmol),after 4 h of vigorous stirring at room temperature]. The combinedmixture was stirred at room temperature for 24 h, and then evaporated todryness. The residue was suspended in water (250 mL) and extracted withEtOAc (2×500 mL). The combined extracts were washed with brine (300 mL),dried over Na₂SO₄, filtered and evaporated. The crude product waspurified on a silica gel column (10 cm×10 cm) using ethyl acetate/hexane(1:3 and 1:2) as the eluent. Fractions containing the product werecombined and evaporated in vacuo to give the desired product (5.05 g) asa colorless foam.

¹H NMR (CDCl₃): δ 0.93 (s, 3H, CH₃), 3.09 (s, 1H, OH), 3.78 (dd, 1H,J_(5′,5″)=10.9 Hz, J_(5′,4)=2.5 Hz, H-5′), 3.99 (dd, 1H, J_(5″,4)=2.2Hz, H-5″), 4.23-4.34 (m, 2H, H-3′, H-4′), 4.63, 4.70 (2d, 2H,J_(gem)=12.7 Hz, CH₂Ph), 4.71, 4.80 (2d, 2H, J_(gem)=12.1 Hz, CH₂Ph),6.54 (d, 1H, , J_(5,6)=3.8 Hz, H-5), 7.23-7.44 (m, 10H, 2Ph).

¹³C NMR (CDCl₃): δ 21.31, 69.10, 70.41, 70.77, 79.56, 80.41, 81.05,91.11, 100.57, 118.21, 127.04, 127.46, 127.57, 129.73, 129.77, 130.57,130.99, 133.51, 133.99, 134.33, 134.38, 134.74, 135.21, 151.07, 151.15152.47.

Step E:4-Chloro-7-(2-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine

To a solution of the compound from Step D (5.42 g, 8.8 mmol) indichloromethane (175 mL) at −78° C. was added boron trichloride (1M indichloromethane, 88 mL, 88 mmol) dropwise. The mixture was stirred at−78° C. for 2.5 h, then at −30° C. to −20° C. for 3 h. The reaction wasquenched by addition of methanol/dichloromethane (1:1) (90 mL) and theresulting mixture stirred at −15° C. for 30 min., then neutralized withaqueous ammonia at 0° C. and stirred at room temperature for 15 min. Thesolid was filtered and washed with CH₂Cl₂/MeOH (1/1, 250 mL). Thecombined filtrate was evaporated, and the residue was purified by flashchromatography over silica gel using CH₂Cl₂ and CH₂Cl₂:MeOH (99:1, 98:2,95:5 and 90:10) gradient as the eluent to furnish desired compound (1.73g) as a colorless foam, which turned into an amorphous solid aftertreatment with MeCN.

¹H NMR (DMSO-d₆) δ 0.64 (s, 3H, CH₃), 3.61-3.71 (m, 1H, H-5′), 3.79-3.88(m, 1H, H-5″), 3.89-4.01 (m, 2H, H-3′, H-4′), 5.15-5.23 (m, 3H, 2′-OH,3′-OH, 5′-OH), 6.24 (s, 1H, H-1′), 6.72 (d, 1H, J_(5,6)=3.8 Hz, H-5),8.13 (d, 1H, H-6), 8.65 (s, 1H, H-2).

¹³C NMR (DMSO-d₆) δ 20.20, 59.95, 72.29, 79.37, 83.16, 91.53, 100.17,117.63, 128.86, 151.13, 151.19, 151.45.

Step F:4-Amino-7-(2-C-methyl-(β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine

To the compound from Step E (1.54 g, 5.1 mmol) was added methanolicammonia (saturated at 0° C.; 150 mL). The mixture was heated in astainless steel autoclave at 85° C. for 14 h, then cooled and evaporatedin vacuo. The crude mixture was purified on a silica gel column withCH₂Cl₂/MeOH (9/1) as eluent to give the title compound as a colorlessfoam (0.8 g), which separated as an amorphous solid after treatment withMeCN. The amorphous solid was recrystallized from methanol/acetonitrile;m.p. 222° C.

¹H NMR (DMSO-d₆): δ 0.62 (s, 3H, CH₃), 3.57-3.67 (m, 1H, H-5′),3.75-3.97 (m, 3H, H-5″, H-4′, H-3′), 5.00 (s, 1H, 2′-OH), 5.04 (d, 1H,J_(3′OH,3′)=6.8 Hz, 3′-OH), 5.06 (t, 1H, J_(5′OH,5′,5″)=5.1 Hz, 5′-OH),6.11 (s, 1H, H-1′), 6.54 (d, 1H, J_(5,6)=3.6 Hz, H-5), 6.97 (or s, 2H,NH₂), 7.44 (d, 1H, H-6), 8.02 (s, 1H, H-2).

¹³C NMR (DMSO-d₆): δ 20.26, 60.42, 72.72, 79.30, 82.75, 91.20, 100.13,103.08, 121.96, 150.37, 152.33, 158.15.

LC-MS: Found: 279.10 (M−H⁺); calc. for C₁₂H₁₆N₄O₄+H⁺: 279.11.

EXAMPLE 634-Amino-7-(3-deoxy-3-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-5-carboxamide

Step A:4-Amino-6-bromo-7-(2-O-acetyl-5-O-benzoyl-3-deoxy-3-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-5-carbonitrile

BSA (0.29 mL, 2.0 mmol) was added into a stirred suspension of4-amino-6-bromo-5-cyano-1H-pyrrolo[2,3-d]pyrimidine (0.24 g, 1 mmol;prepared according to Nucleic Acid Chemistry, Part IV, Townsend, L. B.and Tipson, R. S.; Ed.; Wiley-Interscience: New York, 1991, pp. 16-17and Synthetic Commun. 1998, 28, 3835) in dry acetonitrile (10 mL) atroom temperature under argon. After 15 min,1,2-di-O-acetyl-5-O-benzoyl-3-deoxy-3-methyl-D-ribofuranose (J. Med.Chem. (1976), 19, 1265) (0.36 g, 1.0 mmol) was added along with TMSOTf(0.54 g, 3 mmol). The mixture was stirred at room temperature for 5 minand then at 80° C. for 0.5 h. The solution was cooled, diluted withethyl acetate (50 mL) and poured into ice-cold saturated aqueous NaHCO₃(15 mL). The layers were separated. The organic layer was washed withbrine (15 mL), dried (Na₂SO₄) and then evaporated. The residue waspurified on silica gel column using a solvent system of hexanes/EtOAc:3/1. Appropriate fractions were collected and evaporated to provide thetitle compound as colorless foam (0.21 g).

Step B:4-Amino-7-(2-O-acetyl-5-O-benzoyl-3-deoxy-3-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-5-carbonitrile

To a suspension of the title compound from Step A (183 mg, 0.35 mmol) inEtOH (9 mL) were added ammonium formate (0.23 g, 3.6 mmol) and 10%palladium on activated carbon (20 mg) and the mixture was heated atreflux for 1.5 h. The hot reaction mixture was filtered through Celiteand washed with hot EtOH. The solvent was removed and the residuetreated with MeOH. The pale yellow solid was filtered thus yielding 105mg of pure title compound. The filtrate was evaporated and purified on asilica gel column with a solvent system of CH₂Cl₂/MeOH: 50/1 to affordan additional 63 mg of title compound as a white solid.

Step C:4-Amino-7-(3-deoxy-3-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-5-carboxamide

A mixture of the compound from Step B (51 mg, 0.12 mmol), ethanolicammonia (5 mL, saturated at 0° C.), aqueous ammonia (5 mL, 30%) andaqueous hydrogen peroxide (1 mL, 35%) was stirred room temperature for 8h. The solution was evaporated and:the residue purified on silica gelcolumn with a solvent system of CH₂Cl₂/MeOH: 10/1 to give the titlecompound as a white solid (28 mg).

¹H-MNR (CD₃OD): δ 1.12 (d, 3H, J=6.8 Hz), 2.40 (m, 1H), 3.76 (dd, 1H,J₁=12.8 Hz, J₂=4.0 Hz), 3.94-4.04 (m, 2H), 4.33 (d, 1H, J=5.4 Hz), 6.13(s, 1H), 8.11 (s, 1H), 8.16 (s, 1H).

EXAMPLE 644-Amino-7-(3-deoxy-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine-5-carboxamide

This compound was prepared following the procedures described in J. Med.Chem. 26: 25 (1983).

EXAMPLE 654-Amino-7-(β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine-5-carboxamide(Sangivamycin)

This compound was obtained from commercial sources.

EXAMPLE 66 7-(2-O-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine

This compound was prepared following the procedures described in J. Org.Chem. 39: 1891 (1974).

EXAMPLE 674-Amino-7-(3-deoxy-3-fluoro-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine-5-carboxamide

This compound was prepared following the procedures described in Chem.Pharm. Bull. 41: 775 (1993).

EXAMPLE 684-Amino-7-(3-deoxy-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine-5-carbonitrile

This compound was prepared following the procedures described in J. Med.Chem. 30: 481 (1987).

EXAMPLE 694-Amino-7-(2-O-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine

This compound was prepared following the procedures described in J. Org.Chem. 39: 1891 (1974).

EXAMPLE 70 3′-Amino-3′-deoxy-2′-O-methyladenosine

This compound is obtained by the methylation of appropriately protected3′-amino-3′-deoxyadenosine derivative (Example 54).

EXAMPLE 714-Amino-7-(3-deoxy-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine

This compound was prepared following the following procedure describedin Can. J. Chem. 55: 1251 (1977).

EXAMPLE 72

General Process to SATE Prodrug Moiety

S-Acyl-2-Thioethyl (SATE) pronucleotides are discussed in C. R. Wagner,V. V. Iyer, and E. J. McIntee, “Pronucleotides: Toward the In VivoDelivery of Antiviral and Anticancer Nucleotides,” Med. Res. Rev., 20:1-35 (2000), which is incorporated by reference herein in its entirety.SATE derivatives of nucleosides are also disclosed U.S. Pat. Nos.5,770,725; 5,849,905; and 6,020,482, the contents of each of which areincorporated by reference herein in their entirety.

Bis(S-acetyl-2-thioethyl)-N,N-diisopropylphosphoramidite:

2-Mercaptoethanol (5 g, 64 mmol) was dissolved in CH₂Cl₂ (50 mL). Tothis solution was added triethylamine (7.67 mL, 57.6 mmol), and thereaction mixture was cooled in an ice bath to 0° C. Acetic anhydride(4.54 mL, 48 mmol) was added dropwise in 10 min, and the reactionmixture was stirred for 1 h at 0° C. The reaction mixture was thenallowed to come to room temperature over a period of 2 h. The reactionmixture was diluted with CH₂Cl₂ (50 mL), washed with water (75 mL), 5%aqueous NaHCO₃ (75 mL) and brine (75 mL). The organic phase was driedover anhydrous Na₂SO₄ and concentrated in vacuo to give an oil. The oilwas then dissolved in anhydrous THF (40 mL) and anhydrous triethylamine(7.76 mL) was, added. To this mixture was added activated molecularsieves (4Å) and was kept at room temperature for 10 min. The reactionmixture was cooled in an ice bath to 0° C. anddiisopropylphosphoramidous dichloride (6.47 g, 32.03 mmol) was added.The reaction mixture was stirred at 0° C. for 2 h under inertatmosphere. Hexane (40 mL) was added to the reaction mixture and theprecipitate formed was filtered. The filtrate was concentrated to onefourth of the volume, purified by loaded silica gel columnchromatography and eluted with hexane containing 3% triethylamine andincremental amount of ethyl acetate (0 to 7%) to give the title compoundas an oil (2.36 g).

¹H NMR (CDCl₃): δ 1.17 (s, 6H), 1.21 (s, 6H), 2.36 (s, 6H), 3.14 (t,J=6.44 Hz), 3.51-3.84 (m, 6H); ¹³C NMR (CDCl₃): δ 24.47, 24.61, 30.48,42.85, 43.1, 61.88, 62.23, 195.26; ¹³P NMR (CDCl₃): δ 146.96.

EXAMPLE 73 2′-O-Methylguanosine-5′-[bis-(S-acetyl-2-thioethyl)phosphate]

Step A:N²⁻(4-monomethoxytrityl)-2′-O-methylguanosine-5′-[bis-(S-acetyl-2-thioethyl)phosphate]

N²⁻(4-monomethoxytrityl)-2′-O-methylguanosine (0.74 g, 1.31 mmol) wasmixed with 1H-tetrazole (0.061 g, 0.87 mmol) and dried over P₂O₅ invacuo overnight. To this mixture was added anhydrous acetonitrile (8mL). To the turbid solution,bis(S-acetyl-2-thioethyl)N,N-diisopropylphosphoramidite (0.3 g, 0.87mmol) was added slowly and the reaction mixture was stirred at ambienttemperature under inert atmosphere for 2 h. Solvent was removed invacuo. The residue was cooled to −40° C. and a solution of3-chloroperbenzoic acid (0.2 g) in CH₂Cl₂ (7 mL) was added. The solutionwas allowed to warm up to room temperature over 1 h. Sodiumhydrogensulfite (10% aqueous solution, 2 mL) was added to reduce theexcess of 3-chloroperbenzoic acid. The organic phase separated, dilutedwith CH₂Cl₂ (20 mL), washed with saturated aqueous Na₂CO₃ (10 mL), water(10 mL), dried over Na₂SO₄ and evaporated to dryness. The residue waspurified by silica gel column chromatography and eluted with CH₂Cl₂containing incremental amount of MeOH (5 to 10%) as eluent to yield thetitle compound (0.36 g) as a foam.

¹H NMR (MSO-d₆): δ 2.35 (s, 6H), 2.97 (s, 3H), 3.11 (t, 4H, J=6.0 Hz),3.5 (m, 1H), 3.74 (s, 3H), 3.72-3.83 (m, 2H), 3.97-4.11 (m, 6H), 5.1 (d,1H, J=6.4 Hz), 5.29 (d, 1H, J=3.1 Hz), 6.89 (d, 2H, J=8.8 Hz), 7.15-7.37(m, 12H), 7.68 (s, 1H), 7.73 (s, 1H), 10.72 (s, 1H); ¹³C NMR (CDCl₃): δ30.36, 55.38, 57.99, 66.08, 66.19, 67.22, 69.15, 70.49, 81.18, 81.57,86.64, 113.04, 117.99, 126.66, 127.71, 128.67, 130.04, 136.09, 136.56,144.51, 144.82, 149.52, 151.29, 158.15, 194.56; ¹³P NMR (CDCl₃): δ−2.04; MS (API-ES) 852.10 [M−H]⁺.

Step B: 2′-O-methylguanosine-5′-[bis-(S-acetyl-2-thioethyl)phosphate]

N²⁻(4-monomethoxytrityl)-2′-O-methylguanosine-5′-[bis-(S-acetyl-2-thioethyl)phosphate](0.2 g, 0.23 mmol) was dissolved in acetic acid: MeOH:H₂O, 3:6:1 andheated at 55° C. for 24 h. Solvent was removed and the residue waspurified by HPLC on reverse phase column (Hamilton PRP-1, 250×22 mm,A=Acetonitrile, B=H₂O 20 to 100 B in 65 min, flow 10 mL min⁻¹).Fractions containing the product were pooled together and evaporated togive the title compound (40% yield).

¹³P NMR (CDCl₃): δ −0.72; MS (API-ES) m/z 582.1 [M+H]⁺.

EXAMPLE 742′-O-Methylguanosine-5′-[bis-(S-pivaloyl-2-thioethyl)phosphate]

Step A: Bis(S-pivaloyl-2-thioethyl)-N,N-diisopropylphosphoramidite

S-pivaloyl-2-thioethanol (6.3 g, 39.6 mmol) was dissolved in anhydrousTHF (100 mL). To this solution was added activated molecular sieves (4Å) and kept at room temperature for 30 min. Anhydrous triethylamine (7.9mL, 59.4 mmol) was added and the reaction mixture was cooled in an icebath to 0° C. To this mixture diisopropylphosphoramidous dichloride (4g, 19.8 mmol) was added dropwise. The mixture was stirred the reactionmixture at 0° C. for 2 h under inert gas atmosphere. Hexane (100 mL) wasadded to the reaction mixture, and the precipitate formed was filtered.The filtrate was concentrated to one fourth of the volume. This waspurified by flash silica gel column chromatography using hexanecontaining 2% triethylamine and incremental amount of ethyl acetate (0to 3%) as eluent to give the title compound as an oil (5.23 g).

¹H NMR (CDCl₃): δ 1.13-1.31 (m, 30H), 1.21 (s, 6H), 3.09 (t, J=6.6 Hz,4H), 3.51-3.84 (m, 6H); ¹³C NMR (CDCl₃): δ 24.47, 24.61, 27.32, 30.00,42.85,43.1, 46.32, 61.98, 62.33, 206.1; ¹³P NMR (CDCl₃): δ 148.51.

Step B: 2′-O-methylguanosine-5′-[bis-(S-pivaloyl-2-thioethyl)phosphate]

N²-(4-monomethoxytrityl)-2′-O-methylguanosine (0.6 g, 1.05 mmol) wasmixed with 1H-tetrazole (0.05 g, 0.7 mmol) and dried over P₂O₅ in vacuoovernight. To this mixture anhydrous acetonitrile (13.8 mL) was added.The reaction mixture was cooled to 0° C. in an ice bath andbis(S-pivaloyl-2-thioethyl)N,N-diisopropylphosphoramidite (0.32 g, 0.7mmol) was added slowly. The reaction mixture was stirred at 0° C. for 5minutes. The ice bath was removed and the reaction mixture was allowedto stir at room temperature under an inert atmosphere for 2 h. Solventwas removed in vacuo. The residue was cooled to 40° C. and a solution of3-chloroperbenzoic acid (0.24 g, 1.4 mmol, 57-80%) in CH₂Cl₂ (10 mL) wasadded. The solution was allowed to warm up to −10° C. over 1 h. Sodiumhydrogensulfite (10% aqueous solution, 10 mL) was added to reduce theexcess of 3-chloroperbenzoic acid. The organic phase separated, dilutedwith CH₂Cl₂ (50 mL), washed with saturated aqueous Na₂CO₃ (40 mL), water(40 mL), dried over Na₂SO₄ and evaporated to dryness. The residue waschromatographed on a flash silica gel column using a CH₂Cl₂ containingincremental amount of MeOH (0 to 5%) as eluent. Fractions containing theproduct were pooled together and evaporated. The residue was dissolvedin a solution of acetic acid/water/methanol (10 mL, 3:1:6) and heated at55° C. for 24 h. Evaporated the solution in vacuum to get an oil. Theoil was dissolved in 20% MeOH in water and purified by HPLC on C-18column (Luna C-18, 250×2.12 mm, A=water, B=acetonitrile, 20 to 10% B in65 min., flow 10 mL min⁻¹, λ 260 nm) to yield the title compound (0.082g).

¹H NMR (DMSO-d₆): δ 1.18 (s, 18H), 3.08 (m, 4H), 3.33 (s, 3H) 3.94-4.10(m, 6H), 4.14-4.21 (m, 2H), 4.29 (m, 1H), 5.42 (d, 1H, J=5.4 Hz), 5.81(d, 1H, J=5.8 Hz), 6.49 (bs, 2H), 7.86 (s, 1H), 10.66 (bs, 1H); ¹³P NMR(DMSO-d₆): δ −0.71; MS (API-ES) m/z 664.2 [M−H]⁻.

EXAMPLE 758-Bromo-2′-O-methylguanosine-5′-[bis-(S-pivaloyl-2-thioethyl)phosphate]

This compound was synthesized according to the procedure used for thesynthesis of Example 74 starting with8-bromo-N²-(4-monomethoxytrityl)-2′-O-methylguanosine (0.46 g, 0.63mmol). Other reagents used were 1H-tetrazole (0.034 g, 0.49 mmol),bis(S-pivaloyl-2-thioethyl)N,N-diisopropylphosphoramidite (0.22 g, 0.49mmol), acetonitrile (8.3 ml), 3-chloroperbenzoic acid (0.17 g, 0.98mmol, 57-80%) in CH₂Cl₂ (4 mL). The title compound was isolated in 13%yield (0.061 g).

¹H NMR (DMSO-d₆): δ 1.14 and 1.16 (m, 18H), 3.06 (m, 4H), 3.32 (s, 3H)3.96-4.06 (m, 5H), 4.18-4.3 (m, 2H), 4.46 (d, 1H, J=2.4 Hz), 4.66 (t,1H, J=2.6 Hz), 5.37 (d, 1H, J=2.6 Hz), 5.78 (d, 1H, J=2.8 Hz), 6.62 (bs,2H), 10.99 (bs, 1H); ¹³P NMR (DMSO-d₆) δ −0.79; MS (API-ES) m/z 742.13and 744.13 [M−H]⁻.

EXAMPLE 762-Amino-3,4-dihydro-7-(2-O-methyl-β-D-ribofuranosyl)-4-oxo-7H-pyrrolo[2,3-d]pyrimidine-5′-[bis-(S-pivaloyl-2-thioethyl)phosphate]

This compound was synthesized according to the procedure used for thesynthesis of Example 74 starting with7-deaza-N²-(4-monomethoxytrityl)-2′-O-methylguanosine (0.47 g, 0.82mmol). Other reagents used were 1H-tetrazole (0.044 g, 0.63 mmol),bis(S-pivaloyl-2-thioethyl)N,N-diisopropylphosphoramidite (0.29 g, 0.63mmol), acetonitrile (11 mL), 3-chloroperbenzoic acid (0.21 g, 1.26 mmol,57-80%) in CH₂Cl₂ (5.2 mL). The title compound was isolated in 29% yield(0.158 g).

¹H NMR (DMSO-d₆): δ 1.14 (s, 18H), 3.06 (m, 4H), 3.31 (s, 3H) 3.96-4.26(m, 9H), 5.35 (d, 1H, J=2.6 Hz), 5.78 (d, 1H, J=5.2 Hz), 5.99 (d, 1H,J=6.6 Hz), 6.27 (m, 3H), 6.86 (d, 1H, J=3.6 Hz), 10.39 (s, 1H); ¹³P NMR(DMSO-d₆): δ −0.72; MS (API-ES) m/z 663.20 [M−H]⁻; HRMS Calcd forC₂₆H₄₂N₄O₁₀PS₂ 665.2074 found 665.2071.

EXAMPLE 77 3′-Deoxyguanosine-5′-[bis-(S-pivaloyl-2-thioethyl)phosphate]

N²-(4-Monomethoxytrityl)-3′-deoxyguanosine (0.20 g, 0.35 mmol) was mixedwith 1H-tetrazole (0.019 g, 0.27 mmol) and dried over P₂O₅ in vacuoovernight. To this mixture anhydrous acetonitrile (4.7 mL) was added togive a turbid solution. The reaction mixture was cooled to 0° C. in anice bath and bis(S-pivaloyl-2-thioethyl)N,N-diisopropylphosphoramidite(0.12 g, 0.27 mmol) was added slowly. The reaction mixture was stirredat 0° C. for 5 minutes. The ice bath was removed and the reactionmixture was allowed to come to room temperature. The reaction mixturewas stirred at room temperature under an inert gas atmosphere for 2 h.Solvent was removed in vacuo. The residue was cooled to 40° C. and asolution of 3-chloroperbenzoic acid (0.12 g, 0.7 mmol, 57-80%) in CH₂Cl₂(2.2 mL) was added. The solution was allowed to warm up to −10° C. over1 h. Sodium hydrogensulfite (10% aqueous solution, 2 mL) was added toreduce the excess of 3-chloroperbenzoic acid. The organic phase wasseparated, diluted with CH₂Cl₂ (30 mL), washed with saturated aqueousNa₂CO₃ (20 mL), water (20 mL), dried over Na₂SO₄ and evaporated todryness. The residue was chromatographed on a flash silica gel columnusing CH₂Cl₂ containing incremental amount of MeOH (0 to 5%) as eluent.Fractions containing the product were pooled and evaporated. The residuewas dissolved in a solution of acetic acid/water/methanol (5 mL, 3:1:6)and heated at 55° C. for 24 h. Evaporated the solution in vacuum to getan oil. The oil was dissolved in 20% MeOH in water and purified by HPLCon C-18 column (Luna C-18, 250×2.12 mm, A=water, B=acetonitrile, 20 to10% B in 65 min., flow 10 mL min⁻¹, λ 260 nm) to yield the titlecompound (0.027 g).

¹H NMR (DMSO-d₆): δ 1.15 (s, 18H), 1.92-2.01 (m, 1H), 2.17-2.28 (m, 1H),3.04 (t, 4H, J=6.2 Hz), 3.91-4.23 (m, 6 H), 4.37-4.55 (m, 2H), 5.67 (m,2H), 6.45 (bs, 2H), 7.75 (s, 1H), 10.61 (s, 1H); ¹³P NMR (DMSO-d₆): δ−0.75; MS (API-ES) m/z 634.2 [M−H]⁻.

EXAMPLE 782-Amino-7-(3-deoxy-β-D-ribofuranosyl)-3,4-dihydro-4-oxo-7H-pyrrolo[2,3-d]pyrimidine-5′-[bis-(S-pivaloyl-2-thioethyl)phosphate]

2-(4-Monomethoxytrityl)amino-7-(3-deoxy-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-one(0.30 g, 0.52 mmol) was mixed with 1H-tetrazole (0.028 g, 0.40 mmol) anddried over P₂O₅ in vacuo overnight. To this mixture anhydrousacetonitrile (7 mL) was added, and the solution was cooled to 0° C. inan ice bath. Bis(S-pivaloyl-2-thioethyl)-N,N-diisopropylphosphoramidite(0.18 g, 0.40 mmol) was added slowly. The reaction mixture was allowedto come to at room temperature and stirred at room temperature under aninert atmosphere for 2 h. The solvent was removed in vacuo. The residuewas cooled to 40° C., and a solution of 3-chloroperbenzoic acid (0.14 g,0.8 mmol, 57-80%) in CH₂Cl₂ (5 mL) was added. The solution was allowedto warm up to −10° C. over 2 h. Sodium hydrogensulfite (10% aqueoussolution, 5 mL) was added to reduce the excess of 3-chloroperbenzoicacid. The organic phase was separated, diluted with CH₂Cl₂ (50 mL),washed with saturated aqueous Na₂CO₃ (40 mL), water (40 mL), dried overNa₂SO₄ and evaporated to dryness. The residue was chromatographed on aflash silica gel column using CH₂Cl₂ containing incremental amount ofMeOH (0 to 5%) as eluent. Fractions containing the product were pooledand evaporated. The residue was dissolved in a solution of aceticacid/water/methanol (10 mL, 3:1:6) and heated at 55° C. for 24 h. Thesolution was evaporated to give an oil. The oil was dissolved in 20%MeOH in water and purified by HPLC on C-18 column (Luna C-18,250×2.12mm, A=water, B=acetonitrile 20 to 10% B in 65 mL, flow 10 mL/min, λ 260nm) to give the title compound (0.053 g).

¹H NMR (DMSO-d₆): δ 1.16 (s, 18H), 1.91-2.01 (m, 1H), 2.17-2.25 (m, 1H),3.05 (t, 4H, J=6.2 Hz), 3.92-4.2 (m, 6H), 4.35 (bs, 2H), 5.56 (d, 1H,J=4.2 Hz), 5.86 (d, 1H, J=2.4 Hz), 6.24 (m, 3H), 6.77 (d, 1H, J=3.6 Hz),10.36 (s, 1H); ¹³P NMR DMSO-d₆): δ −0.89; HRMS (MALDI) Calcd forC₂₅H₃₉N₄O₉PS₂.635.1969 found 635.1964.

EXAMPLE 792-Amino-5-bromo-7-(3-deoxy-β-D-ribofuranosyl)-3,4-dihydro-4-oxo-7H-pyrrolo[2,3-d]pyrimidine-5′-[bis-(S-pivaloyl-2-thioethyl)phosphate]

2-(4-Monomethoxytrityl)amino-5-bromo-7-(3-deoxy-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-one(0.066 g, 0.17 mmol) was mixed with imidazole triflate (0.017 g, 0.17mmol) and dried over P₂O₅ in vacuo overnight. To this mixture anhydrousacetonitrile (7 mL) andbis(S-pivaloyl-2-thioethyl)N,N-diisopropylphosphoramidite (0.97 g, 0.24mmol) were added slowly. The reaction mixture was stirred under an inertatmosphere for 18 h. Solvent was removed in vacuo. The residue wascooled to −40° C. and a solution of 3-chloroperbenzoic acid (0.059 g,0.34 mmol, 57-80%) in CH₂Cl₂ (2 mL) was added. The solution was allowedto warm up to −10° C. over 2 h. Sodium hydrogensulfite (10% aqueoussolution, 5 mL) was added to reduce the excess of 3-chloroperbenzoicacid. The organic phase was separated, diluted with CH₂Cl₂ (30 mL),washed with saturated aqueous Na₂CO₃ (20 mL), water (20 mL), dried overNa₂SO₄ and evaporated to dryness. The residue was chromatographed onflash silica gel column using CH₂Cl₂ containing incremental amount ofMeOH (0 to 5%) as eluent. Fractions containing the product were pooledand evaporated. The residue was dissolved in a solution of aceticacid/water/methanol (3 mL, 3:1:6) and heated at 55° C. for 24 h. Thesolution was evaporated to give an oil. The oil was dissolved in 20%MeOH in water and purified by HPLC on C-18 column (Luna C-18,250×2.12mm, A=water, B=acetonitrile 20 to 10% B in 65 mL, flow 10 mL min⁻¹, λ260 nm) to afford the title compound (0.036 g).

¹H NMR (DMSO-d₆): δ 1.17 (s, 18H), 1.87-2.03 (m, 1H), 2.17-2.26 (m, 1H),3.05 (t, 4H, J=6.4 Hz), 3.92-4.2 (m, 6H), 4.37 (bs, 2H), 5.70 (d, 1H,J=4.4 Hz), 5.85 (d, 1H, J=2.6 Hz), 6.36 (bs, 2H), 6.93 (s, 1H), 10.51(s, 1H); ¹³P NMR (DMSO-d₆): δ −0.89; MS (AP-ES) m/z 711.11 and 713.09[M−H]⁻; HRMS (MALDI) Calcd for C₂₅H₃₈BrN₄O₉PS₂.713.1074 and 715.1074found 713.1081 and 715.102.

EXAMPLE 802′-O-Methylcytidine-5′-[bis-(S-pivaloyl-2-thioethyl)phosphate]

N⁴-(4,4′-Dimethoxytrityl)-2′-O-methylcytidine (0.49 g, 0.86 mmol) wasmixed with 1H-tetrazole (0.06 g, 0.86 mmol) and dried over P₂O₅ in vacuoovernight. To this mixture anhydrous acetonitrile (6 mL) andbis-(S-pivaloyl-2-thioethyl)-N,N-diisopropylphosphoramidite (0.39 g,0.86 mmol) were added at 0° C. The reaction mixture was allowed to cometo room temperature and stirred under an inert atmosphere for 18 h.Solvent was removed in vacuo. The residue was cooled to −40° C. and asolution of 3-chloroperbenzoic acid (0.3 g, 1.72 mmol, 57-80%) in CH₂Cl₂(5.5 mL) was added. The solution was allowed to warm up to −10° C. over2 h. Sodium hydrogensulfite (10% aqueous solution, 5 mL) was added toreduce the excess of 3-chloroperbenzoic acid. The organic phase wasseparated, diluted with CH₂Cl₂ (30 mL), washed with saturated aqueousNa₂CO₃ (20 mL), water (20 mL), dried over Na₂SO₄ and evaporated todryness. The residue was chromatographed on a flash silica gel columnusing CH₂Cl₂ containing incremental amount of MeOH (0 to 10%) as eluent.Fractions containing the product were pooled and evaporated. The residuewas dissolved in a solution of acetic acid/water/methanol (10 mL, 3:1:6)and heated at 55° C. for 24 h. The solution was evaporated to give anoil. The oil was dissolved in 20% MeOH in water and purified by HPLC onC-18 column (Luna C18,250×2.12 mm, A=water, B=acetonitrile 20 to 10% Bin 65 mL, flow 10 mL min⁻¹, λ 260 nm) to yield the title compound (0.076g).

¹H NMR (DMSO-d₆): δ 1.18 (s, 18H), 3.12 (t, 4H, J=6.4 Hz), 3.39 (s, 3H),3.69 (t, 1H, J=4.2 Hz), 3.93-4.3 (m, 8H), 5.29 (d, 1H, J=6.2 Hz), 5.72(d, 1H, J=7.4 Hz), 5.86 (d, 1H, J=4 Hz), 7.21 (bs, 2H), 7.58 (d, 1H,J=7.4 Hz); ¹³P NMR (CD₃CN): δ −0.64; MS (AP-ES) m/z 625.69 [M+H]⁺; HRMS(MALDI) Calcd for C₂₄H₄₀N₃O₁₀PS₂Na 648.1785 found 648.1804.

EXAMPLE 815-Bromo-2′-O-methylcytidine-5′-[bis-(S-pivaloyl-2-thioethyl)phosphate]

Step A: 5-Bromo-3′-O-(t-butyldimethyl)silyl-2′-O-methylcytidine

2′-O-Methylcytidine (1.5 g, 5.83 mmol) was mixed with imidazole (3.97 g,58.32 mmol) and dried in vacuo. This mixture was dissolved in anhydrousDMF (4 mL) and t-butyldimethylsilyl chloride (4.41 g, 29.25 mmol) wasadded and the reaction mixture was stirred for 18 h at room temperatureunder an inert atmosphere. Reaction mixture was diluted with water (100mL) and extracted with ethyl acetate (2×60 mL). The organic phase wasdried over anhydrous Na₂SO₄ and evaporated. The residue was purified bysilica gel column chromatography and eluted with ethyl acetate/hexane,6:4. Fractions containing the product were pooled and evaporated. Theproduct obtained (2.76 g) was dissolved in acetonitrile (19.43 mL), LiBr(0.623 g, 7.18 mmol) and stirred to get a clear solution. To thisammonium ceric (IV) nitrate (6.24 g, 11.37 mmol) was added and thereaction mixture was allowed to stir at room temperature for 3 h.Solvent was removed in vacuum. The residue obtained was taken in ethylacetate (100 mL) and washed with water (80 mL). The organic phase wasseparated, dried over anhydrous Na₂SO₄ and evaporated. Residue purifiedby silca gel column chromatography and eluted with 5% MeOH in CH₂Cl₂.The product obtained (2.66 g) was dissolved in 80% acetic acid in waterand heated at 50° C. for 6 h. The solvent was removed and the residuepurified on a silica gel column and eluted with 5% MeOH in CH₂Cl₂ togive the title compound (0.85 g).

¹H NMR (DMSO-d₆): δ 0.78 (s, 6H), 0.85 (s, 9H), 3.31 (s, 3H), 3.44-3.6(m, 2H), 3.69-3.9 (m, 2H), 4.24 (m, 1H), 5.29 (t, 1H, J=4.4 Hz), 5.76(d, 1H, J=3.2 Hz), 7.06 (bs, 1H), 7.88 (bs, 1H), 8.39 (s, 1H).

Step B:5-Bromo-2′-O-methylcytidine-5′-[bis-(S-pivaloyl-2-thioethyl)phosphate]

5-Bromo-3′-O-(t-butyldimethyl)silyl-2′-O-methylcytidine (0.093 g, 0.21mmol) was mixed with 1H-tetrazole (0.03 g, 0.42 mmol) and dried overP₂O₅ in vacuo overnight. To this mixture anhydrous acetonitrile (2 mL).Bis-(S-pivaloyl-2-thioethyl)-N,N-diisopropylphosphoramidite (0.2 g, 0.42mmol) was added at 0° C. The reaction mixture was allowed to come toroom temperature and stirred under an inert atmosphere for 4 h. Solventwas removed in vacuo. The residue was cooled to −40° C. and a solutionof 3-chloroperbenzoic acid (0.072 g, 0.42 mmol, 57-80%) in CH₂Cl₂ (2 mL)was added. The solution was allowed to warm up to −10° C. over 2 h.Sodium hydrogensulfite (10% aqueous solution, 2 mL) was added to reducethe excess of 3-chloroperbenzoic acid. The organic phase separated,diluted with CH₂Cl₂ (30 mL), washed with saturated aqueous Na₂CO₃ (20mL), water (20 mL), dried over Na₂SO₄ and evaporated to dryness. Theresidue was dissolved in THF (2.1 mL) and triethylamine trihydrofluoride(0.17 g, 1.1 mmol). The reaction mixture was stirred at room temperaturefor 18 h. The solution was evaporated to give an oil. The oil wasdissolved in ethyl acetate (30 mL) and washed with water (20 mL), 5%aqueous NaHCO₃ and brine (20 mL). The organic phase was dried overanhydrous Na₂SO₄ and evaporated. The residue was dissolved in 20% MeOHin water and purified by HPLC on C-18 column (Luna C18, 250×2.12 mm,A=water, B=acetonitrile 20 to 10% B in 65 mL, flow 10 mL min⁻¹, λ260 nm)to give the title compound (0.054 g).

¹H NMR (DMSO-d₆): δ 1.17 (s, 18H), 3.11 (t, 4H, J=6.2 Hz), 3.39 (s, 3H),3.75 (t, 1H, J=4.8 Hz), 3.934.3 (m, 8H), 5.23 (d, 1H, J=6.4 Hz), 5.8 (d,1H, J=3.8 Hz), 7.07 (bs, 1H), 7.89 (s, 1H) 7.94 (bs, 1H); ¹³P NMR(CD₃CN): δ −0.34; MS (AP-ES) m/z 702.00 and 704.00 [M−H]⁻; HRMS (MALDI)Calcd for C₂₄H₃₉BrN₃O₁₀PS₂Na 726.0890 and 728.0890 found 726.0893 and728.086.

EXAMPLE 82 3′-Deoxycytidine-5′-[bis-(S-pivaloyl-2-thioethyl)phosphate]

Step A: N⁴-(4,4′-dimethoxytrityl)-3′-deoxycytidine

3′-Deoxycytidine (0.8 g, 3.54 mmol) was mixed with imidazole (2.41 g,35.4 mmol) and dried over P₂O₅ in vacuum overnight at 40° C. The mixturewas dissolved in anhydrous DMF and t-butyldimethylsilyl chloride (2.68g, 17.78 mmol) was added and the reaction mixture was stirred under anargon atmosphere for 18 h at room temperature. The reaction mixture wasdiluted with water (100 mL) and extracted with ethyl acetate (2×75 mL).The organic phase was separated, dried over anhydrous Na₂SO₄ andevaporated. The residue was purified by silica gel column chromatographyand eluted with ethyl acetate/hexane (6:4) to yield2′,5′-bis(t-butyldimethylsilyl)-3′-deoxycytidine (1.27 g). This was thenmixed with DMAP (0.34 g, 2.79 mmol) and dried in vacuum. This mixturewas dissolved in anhydrous pyridine (8 mL) and 4,4′-dimethoxytritylchloride (1.89 g, 5.58 mmol) was added. The reaction mixture was stirredat room temperature under an argon atmosphere for 18 h. Solvent wasremoved in vacuo. The residue obtained was taken in ethyl acetate (100mL) and washed with 5% NaHCO₃ in water (75 mL) and brine (75 ml). Theorganic phase was dried over anhydrous Na₂SO₄ and evaporated. Theresidue obtained was dissolved in THF (28 mL). To this triethylaminetrihydrofluoride (2.26 mL, 13.74 mmol) and triethylamine (0.95 mL, 6.87mmol) were added and stirred at room temperature for 18 h. Solvent wasremoved and the residue dissolved in ethyl acetate (50 mL), washed withwater (50 mL) and 5% NaHCO₃ in water (50 mL). The organic phase wasdried over anhydrous Na₂SO₄ and evaporated. The residue obtained waspurified by silica gel column chromatography and eluted with 5% MeOH inCH₂Cl₂ to yield the title compound (0.66 g).

¹H NMR (DMSO-d₆): δ 1.66 (m, 1H), 1.85 (m, 1H1), 3.47 (m, 1H), 3.63 (m,1H), 3.71 (s, 6H), 4.00 (bs, 1H), 4.19 (m, 1H), 4.96 (t, 1H, J 5.2 Hz),5.39 (bs, 1H), 5.53 (s, 1H), 6.17 (bs, 1H), 6.83 (d, 4H, J=8.8 Hz),7.04-7.22 (m, 9H), 7.77 (d, 1H, J=7.6 Hz), 8.27 (bs, 1H); MS (AP-ES) m/z528.1 [M−H]³¹.

Step B: 3′-Deoxycytidine-5′-[bis-(S-pivaloyl-2-thioethyl)phosphate]

This compound was synthesized following the similar synthetic procedureused for the synthesis of Example 80 starting withN⁴-(4,4′-dimethoxytrityl)-3′-deoxycytidine (0.3 g, 0.57 mmol). Otherreagents used for the synthesis were 1H-tetrazole (0.04 g, 0.57 mmol),acetonitrile (4 mL),bis-(S-pivaloyl-2-thioethyl)-N,N-diisopropylphosphoramidite (0.52 g,1.14 mmol) and 3-chloroperbenzoic acid (0.2g, 1.14 mmol, 57-80%) inCH₂Cl₂ (3.6 mL). The product was isolated in 22% yield (0.073 g) afterHPLC purification.

¹H NMR (200 MHz, DMSO-d₆): δ 1.17 (s, 18H), 1.84 (m, 2H), 3.11 (t, 4H,J=6.4 Hz), 3.93-4.31 (m, 8H), 4.39 (m, 1H), 5.55 (d, 1H, J=4.2 Hz),5.67(dd, 2H, J=7.4 and 1.8 Hz), 7.1 (bs, 2H), 7.56 (d, 1H, J=7.4 Hz);¹³P NMR (CD₃CN): δ −0.71; MS (AP-ES) m/z 596.1 [M+H]⁺; HRMS (MALDI)Calcd for C₂₃H₃₈N₃O₉PS₂Na 618.1679 found 618.1600.

EXAMPLE 832′-O-Methylcytidine-5′-[bis-(isoprovyloxycarbonyloxymethyl)]phosphate

Phosphonomethoxy nucleoside analogs are discussed in C. R. Wagner, V. V.Iyer, and E. J. McIntee, “Pronucleotides: Toward the In Vivo Delivery ofAntiviral and Anticancer Nucleotides,” Med. Res. Rev., 20: 1-35 (2000),which is incorporated by reference herein in its entirety. They are alsodisclosed U.S. Pat. Nos. 5,922,695; 5,977,089; 6,043,230; and 6,069,249,the contents of each of which are incorporated by reference herein intheir entirety.

Step A: iso-Propyl chloromethyl carbonate

This was prepared according to Antiviral Chemistry & Chemotherapy 8: 557(1997).

Step B: 2′-O-Methylcytidine-5′-phosphate

This intermediate was prepared as described in Tetrahedron Lett. 50:5065 (1967).

Step C:2′-O-Methylcytidine-5′-[bis(isopropyloxycarbonyloxymethyl)]phosphate

2′-O-Methylcytidine-5′-phosphate (0.4 g, 1.19 mmol) was dried over P₂O₅in vacuum overnight at 40° C. It was then suspended in anhydrous DMF (4mL). To this mixture was added diisopropylethylamine (0.86 mL, 4.92mmol) and iso-propyl chloromethyl carbonate (1.56 g, 7.34 mmol). Themixture was heated at 50° C. for 1 h. The reaction mixture was thenallowed to come to room temperature. The reaction mixture was stirred atroom temperature for 48 h and then filtered. The filtrate was dilutedwith water (100 mL) and extracted with CH₂Cl₂ (3×50 mL). The organicphase was dried over anhydrous Na₂SO₄ and evaporated. The residue wasdissolved in 20% MeOH in water and purified by HPLC on C-18 column (LunaC18,250×2.12 mm, A=water, B=acetonitrile 20 to 10% B in 65 ML, flow 10mL min⁻¹, λ 260 nm) to give the title compound (2.5 mg). ¹³P NMR(CD₃CN): δ −3.09; MS (AP-ES) m/z 570.1 [M+H]⁺.

EXAMPLE 842′-O-Methylcytidine-5′-[(2-decyloxy-3-dodecylthio-1-propyl)phosphate]

The procedure is described for similar nucleoside analogs in GermanPatent 408366 (1992) and J. Acquired Immune Defic. Syndr.2000, 23, 227.The reaction of the appropriately protected 2′-O-methylcytidine with(2-decyloxy-3-dodecylthio-1-propyl)phosphate [prepared by the reactionof 2-decyloxy-3-dodecylthio-1-propanol with POCl₃ in ether in presenceof triethylamine] under refluxing conditions in a toluene-ether mixturefurnishes the desired compound.

EXAMPLE 852′-O-Methylcytidine-5′-[rac-(3-octadecylthio-2-palmitoyloxy-1-propyl)phosphate]

This compound is synthesized by the reaction of2′-O-methylcytidine-5′-monophosphoromorpholidate withrac-1-S-octadecyl-2-O-palmitoyl-1-thioglycerol in pyridine following thesimilar procedure described for AZT and ddC in J. Med. Chem. 39: 1771(1996).

EXAMPLE 86

Nucleoside 5′-Triphosphates

The nucleoside 5′-triphosphates of the present invention were preparedaccording to the general procedures described in Chem. Rev.100: 2047(2000).

EXAMPLE 87

Purification and Purity Analysis of Nucleoside 5′-Triphosphates

Triphosphates were purified by anion exchange (AX) chromatography usinga 30×100 mm Mono Q column (Pharmacia) with a buffer system of 50 mMTris, pH 8. Elution gradients were typically from 40 mM NaCl to 0.8 MNaCl in two column volumes at 6.5 mL/min. Appropriate fractions fromanion exchange chromatography were collected and desalted byreverse-phase (RP) chromatography using a Luna C18 250×21 mm column(Phenomenex) with a flow rate of 10 ml/min. Elution gradients weregenerally from 1% to 95% methanol in 14 min at a constant concentrationof 5 mM triethylammonium acetate (TEAA).

Mass spectra of the purified triphosphates were determined using on-lineHPLC mass spectrometry on a Hewlett-Packard (Palo Alto, Calif.) MSD1100. A Phenomenex Luna (C18(2)), 150×2 mm, plus 30×2 mm guard column,3-μm particle size was used for RP HPLC. A 0 to 50% linear gradient (15min) of acetonitrile in 20 mM TEAA (triethylammonium acetate) pH 7 wasperformed in series with mass spectral detection in the negativeionization mode. Nitrogen gas and a pneumatic nebulizer were used togenerate the electrospray. The mass range of 150-900 was sampled.Molecular masses were determined using the HP Chemstation analysispackage.

The purity of the purified triphosphates was determined by analytical RPand AX HPLC. RP HPLC with a Phenomonex Luna or Jupiter column (250×4.6mm), 5-μm particle size was typically run with a 2-70% acetonitrilegradient in 15 min in 100 mM TEAA, pH 7. AX HPLC was performed on a1.6×5 mm Mono Q column (Pharmacia). Triphosphates were eluted with agradient of 0 to 0.4 M NaCl at constant concentration of 50 mM Tris, pH8. Purity of the triphosphates was generally >80%.

EXAMPLE 88 Nucleoside 5′-Monophosphates

The nucleoside 5′-monophosphates of the present invention were preparedaccording to the general procedure described in Tetrahedron Lett. 50:5065 (1967).

EXAMPLE 89 2-Amino-9-(β-D-arabinofuranosyl)-9H-purin-6(1H)-one

This compound was obtained from commercial sources.

EXAMPLE 90 3′-Deoxy-3′-methylguanosine

This compound was prepared following procedures described in U.S. Pat.No. 3,654,262 (1972).

EXAMPLE 91 2′-O-[4-(Imidazolyl-1)butyl]guanosine

Step A: 2′-O-[4-(Imidazolyl-1)butyl]-2-aminoadenosine

A solution 2-aminoadenosine (7.36 g, 26 mmol) in dry DMF (260 mL) wastreated portionwise with 60% NaH (3.92 g, 1000 mmol). After 1 hr., asolution of bromobutylimidazole (9.4 g, 286 mmol) in DMF (20ml) wasadded. After 16 hrs., the solution was conc. in vacuo, partitionedbetween H₂O/EtOAc and separated. The aqueous layer was evaporated, andthe residue was chromatographed on silica gel (CHCl₃/MeOH) to afford thetitle nucleoside as a white solid; yield 4.2 g.

¹H NMR (DMSO-d₆): δ 1.39 (t, 2H), 1.67 (t, 2H), 3.3-3.7 (m, 4H), 3.93(m, 3H), 4.29 (m, 2H), 4.40 (d, 1H), 5.50 (5, 1H), 5.72 (d, 1H), 5.82(bs, 2H), 6.72 (bs, 2H), 6.86 (s, 1H), 7.08 (s, 1H), 7.57 (s, 1H). 7.91(s, 1H).

Step B: 2′-O-[4-(Imidazolyl-1)butyl]guanosine

A mixture of the intermediate from Step A (3.2 g, 8 mmol) in H₂O (200mL), DMSO (10 mL), trisodium phosphate (10 g), and adenosine deaminase(0.3 g) was stirred at room temperature and pH 7. The solution wasfiltered and and then evaporated. The resulting solid was crystallizedfrom EtOAc/MeOH to afford the title compound as a white solid; yield 2.6g.

¹H NMR (DMSO-d₆): δ 1.39 (t, 2H), 1.67 (t, 2H), 3.3-3.7 (m, 4H), 3.93(m, 3H), 4.29 (m, 2H), 5.10 (t, 1H), 5.20 (d, 1H), 5.79 (d, 1H), 6.50(bs, 2H), 6.86 (s, 1H), 7.08 (s, 1H), 7.57 (s, 1H) 7.9 (s, 1H).

EXAMPLE 92 2′-Deoxy-2′-fluorogulanosine

This compound was prepared following the conditions described in Chem.Pharm. Bull. 29: 1034 (1981).

EXAMPLE 93 2′-Deoxyguanosine

This compound was obtained from commercial sources.

EXAMPLE 942-Amino-7-(2-deoxy-2-fluoro-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-one

Step A:2-Amino-4-chloro-7-(2,3,5-tri-O-benzyl-β-D-arabinofuranosyl)-7H-pyrrolo[2,3-d]-pyrimidine

To a suspension of 2-amino-4-chloro-1H-pyrrolo[2,3-d]pyrimidine [LiebigsAnn. Chem. 1: 137 (1983)] (3.03 g, 18 mmol) in anhydrous MeCN (240 mL),powdered KOH (85%; 4.2 g, 60 mmol) andtris[2-(2-methoxyethoxy)-ethyl]amine (0.66 mL, 2.1 mmol) were added andthe mixture was stirred at room temperature for 10 min. Then a solutionof 2,3,5-tri-O-benzyl-D-arabinofuranosyl bromide [prepared fromcorresponding 1-O-p-nitrobenzoate (11.43 g, 20.1 mmol) according toSeela et al., J. Org. Chem. (1982), 47, 226] in MeCN (10 mL) was addedand stirring continued for another 40 min. Solid was filtered off,washed with MeCN (2×25 mL) and combined filtrate evaporated. The residuewas purified on a silica gel column with a solvent system ofhexanes/EtOAc: 7/1, 6/1 and 5/1. Two main zones were separated. From themore rapidly migrating zone was isolated the α anomer (0.74 g) and fromthe slower migrating zone the desired β anomer (4.01 g).

Step B:2-Amino-7-(β-D-arabinofuranosyl)-4-chloro-7H-pyrrolo[2,3-d]pyrimidine

To a solution of the compound from Step A (4.0 g, 7 mmol) in CH₂Cl₂ (150ml) at −78° C. was added a solution of 1.0 M BCl₃ in CH₂Cl₂ (70 mL, 70mmol) during 45 min. The mixture was stirred at −78° C. for 3 h and at−20° C. for 2.5 h. MeOH—CH₂Cl₂ (70 mL, 1:1) was added to the mixture,which was then stirred at −20° C. for 0.5 h and neutralized with conc.aqueous NH₃ at 0° C. The mixture was stirred at room temperature for 10min. and then filtered. The solid was washed with MeOH—CH₂Cl₂ (70 mL,1:1) and the combined filtrate evaporated. The residue was purified on asilica gel column with a solvent system of CH₂Cl₂/MeOH: 20/1 to give thedesired nucleoside (1.18 g) as a white solid.

Step C:2-Amino-7-[3,5-O-(1,3,3-tetraisopropyldisiloxane-1,3-diyl)-β-D-arabinofuranosyl]-4-chloro-7H-pyrrolo[2,3-d]pyrimidine

The compound from Step B (0.87 g, 2.9 mmol) and imidazole (0.43 g, 5.8mmol were dissolved in DMF (3.5 mL).1,3-Dichloro-1,1,3,3-tetraisopropyldisiloxane (1.0 mL) was added to thesolution. The reaction mixture was stirred at room temperature for 1 hand then evaporated. The residue was partitioned between CH₂Cl₂ (150 mL)and water (30 mL). The layers were separated. The organic layer wasdried (Na₂SO₄) and evaporated. The residue was purified on a silica gelcolumn with a solvent system of hexanes/EtOAc: 7/1 and 5/1 to give thetitle compound (1.04 g).

Step D:2-Amino-7-[2-O-acetyl-3,5-0-(1,1,3,3-tetraisopropyldisiloxane-1,3-diyl)-β-D-arabinofuranosyl]-4-chloro-7H-pyrrolo[2,3-d]pyrimidine

A mixture of the compound from Step C (0.98 g, 1.8 mmol) in MeCN (12mL), Et₃N (0.31 mL) Ac₂O (0.21 mL) and DMAP (5 mg, 0.25 eq.) was stirredat room temperature for 5 h and then evaporated. The oily-residue wasdissolved in EtOAc (200 mL), washed with water (2×20 mL), dried (Na₂SO₄)and evaporated to yield pure title compound (1.12 g).

Step E:2-Amino-7-[2-O-acetyl-β-D-arabinofuranosyl]-4-chloro-7H-pyrrolo[2,3-d]pyrimidine

To an ice-cold solution of the compound from Step D (0.95 g, 1.63 mmol)in THF (10 mL) and AcOH (0.19 mL) was added dropwise 1.0 Mtetrabutylammonium fluoride solution in THF (3.4 mL) and stirred at 0°C. for 15 min. The solution was concentrated and the oily residueapplied onto a silica gel column packed in CH₂Cl₂ and eluted withCH₂Cl₂/MeOH: 50/1, 25/1 and 20/1. Appropriate fractions were pooled andevaporated to give the title nucleoside (0.56 g) as a white solid.

Step F:2-Amino-7-[2-O-acetyl-3,5-di-O-(tetrahydro-2-pyranyl)-β-D-arabinofuranosyl]-4-chloro-7H-pyrrolo[2,3-d]pyrimidine

To a solution of the compound from Step E (0.5 g, 1.46 mmol) in CH₂Cl₂(10 mL) and 3,4-dihydro-2-H-pyrane (0.67 mL) was added dropwise TMSI (30μL, 0.2 mmol). The reaction mixture was stirred at room temperature for1 h and then evaporated. The oily residue was purified on a silica gelcolumn packed in a solvent system of hexanes/EtOAc/Et₃N: 75/25/1 andeluted with a solvent system of hexanes/EtOAc: 3/1. The fractionscontaining the product were collected and evaporated to give the desiredcompound (0.60 g).

Step G:2-Amino-7-[3,5-di-O-(tetrahydro-2-pyranyl)-β-D-arabinofuranosyl]-4-chloro-7H-pyrrolo[2,3-d]pyrimidine

A mixture of the compound from Step F (0.27 g, 0.53 mmol) and methanolicammonia (saturated at 0° C.; 10 mL) was kept overnight at 0° C.Evaporation of the solvent yielded the desired compound (0.25 g).

Step H:2-Amino-7-[2-deoxy-2-fluoro-3,5-di-O-(tetrahydro-2-pyranyl)-β-D-ribofuranosyl]-4-chloro-7H-pyrrolo[2,3-d]pyrimidine

To a solution of the compound from Step G (0.24 g, 0.51 mmol) in CH₂Cl₂(5 mL) and pyridine (0.8 mL) at −60° C. was added diethylaminosulfurtrifluoride (DAST; 0.27 mL) dropwise under Ar. The solution was stirredat −60° C. for 0.5 h, at 0° C. overnight and at room temperature for 3h. The mixture was diluted with CH₂Cl₂ (25 mL) and poured into saturatedaqueous NaHCO₃ (15 mL). The organic layer was washed with water (10 mL),dried (Na₂SO₄) and evaporated. The residue was purified on a silica gelcolumn with a solvent system of hexanes/EtOAc: 5/1 to give the titlecompound (45 mg) as a pale yellow foam.

Step I:2-Amino-7-(2-deoxy-2-fluoro-β-D-ribofuranosyl)-4-chloro-7H-pyrrolo[2,3-d]-primidine

A solution of the compound from Step H (40 mg. 0.08 mmol) in EtOH (2 mL)was stirred with pyridinium p-toluenesulfonate (40 mg, 0.16 mmol) at 60°C. for 3 h. The mixture was then evaporated and the residue purified ona silica gel column with a solvent system of hexanes/EtOAc: 1/1 and 1/2to give the desired compound (24 mg).

Step J:2-Amino-7-(2-deoxy-2-fluoro-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-one

A mixture of the compound from Step I (4 mg, 0.08 mmol) in 2N aqueousNaOH (1.2 mL) was stirred at reflux temperature for 1.5 h. The solutionwas cooled in an ice-bath, neutralized with 2 N aqueous HCl andevaporated to dryness. The residue was suspended in MeOH, mixed withsilica gel and evaporated. The solid residue was placed onto a silicagel column (packed in a solvent system of CH₂Cl₂/MeOH: 10/1) which waseluted with a solvent system of CH₂Cl₂/MeOH: 10/1. The fractionscontaining the product were collected and evaporated to dryness to yieldthe title compound (20 mg) as a white solid.

¹H NMR (CD₃OD): δ 3.73, 3.88 (2dd, 2H, J=12.4, 3.8, 2.6 Hz), 4.01 (m,1H), 4.47 (ddd, 1H J=16.5, 6.6 Hz), 5.14 (ddd, 1H, J=5.3, 4.7 Hz), 6.19(dd, 1H, J=17.8, 3.0 Hz), 6.39 (d, 1H, J=3.6 Hz), 6.95 (d, 1H).

¹⁹F NMR (CD₃OD): δ −206.53 (dt).

EXAMPLE 952-Amino-7-(β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-one

This compound was prepared following the procedures described in J.Chem. Soc. Perkin Trans. 1, 2375 (1989).

EXAMPLE 962-Amino-7-(2-deoxy-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-one

This compound was prepared following the procedures in Tetrahedron Lett.28: 5107 (1987).

EXAMPLE 976-Amino-1-(2-O-methyl-β-D-ribofuranosyl)-1H-imidazo[4,5-c]pyridin-4(5H)-one

This compound was prepared in a manner similar to the preparation of2-amino-7-(3-deoxy-3-fluoro-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyridin-4(3H)-one(Example 23).

EXAMPLE 986-Amino-1-(2-deoxy-β-D-ribofuranosyl)-1H-imidazo[4,5-c]pyridin-4(5H)-one

This compound was prepared following the procedures described in J. Med.Chem. 26: 286 (1983).

EXAMPLE 996-Amino-1-(3-deoxy-3-methyl-β-D-ribofuranosyl)-1H-imidazo[4,5-c]pyridin-4(5H)-one

This compound was prepared in a manner similar to the preparation of2-amino-7-(3-deoxy-3-fluoro-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-one(Example 23).

EXAMPLE 1006-Amino-1-(2-deoxy-2-fluoro-β-D-ribofuranosyl)-1H-imidazo[4,5-c]pyridin-4(5H)-one

This compound was prepared in a manner similar to the preparation of2-amino-7-(3-deoxy-3-fluoro-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-one(Example 23).

EXAMPLE 1016-Amino-1-(β-D-arabinofuranosyl)-1H-imidazo[4,5-c]pyridin-4(5H)-one

A preparation of this compound is given in Eur. Pat. Appln. 43722 A1(1982).

EXAMPLE 102 2′-O-[2-(N,N-diethylaminooxy)ethyl]-5-methyluridine

Step A:5′-O-tert-Butyldiphenylsilyl-2′-O-(2-hydroxyethyl)-5-methyluridine

In a 2 L stainless steel, unstirred pressure reactor was added borane intetrahydrofuran (1.0 M, 2.0 eq, 622 mL). In the fume hood and withmanual stirring, ethylene glycol (350 mL, excess) was added cautiouslyat first until the evolution of hydrogen gas subsided.5′-O-tert-Butyldiphenylsilyl-O²-2′-anhydro-5-methyluridine (149 g, 0.311mol) and sodium bicarbonate (0.074 g) were added with manual stirring.The reactor was sealed and heated in an oil bath until an internaltemperature of 160° C. was reached and then maintained for 16 h(pressure<100 psig). The reaction vessel was cooled to ambient and opened. Thereaction mixture was concentrated under reduced pressure (10 to 1 mm Hg)in a warm water bath (40-100° C.) with the more extreme conditions usedto remove the ethylene glycol. The residue was purified by columnchromatography (2 kg silica gel, ethyl acetate:hexanes gradient 1:1 to4:1). The appropriate fractions were combined, stripped and dried toproduct as white crisp foam (84 g), contaminated starting material (17.4g) and pure reusable starting material (20 g). TLC and NMR wereconsistent with 99% pure product.

¹H NMR (DMSO-d₆): δ 1.05 (s, 9H), 1.45 (s, 3H), 3.5-4.1 (m, 8H), 4.25(m, 1H), 4.80 (t, 1H), 5.18 (d, 2H), 5.95 (d, 1H), 7.35-7.75 (m, 11H),11.42 (s, 1H).

Step B:2′-O-[2-(2-phthalimidoxy)ethyl]-5′-t-butyldiphenylsilyl-5-methyluridine

5′-O-tert-Butyldiphenylsilyl-2′-O-(2-hydroxyethyl)-5-methyluridine (20g, 36.98 mmol) was mixed with triphenylphosphine (11.63 g, 44.36 mmol)and N-hydroxyphthalimide (7.24 g, 44.36 mmol). It was then dried overP₂O₅ under high vacuum for two days at 40° C. The reaction mixture wasflushed with argon and dry THF (369.8 mL) was added to get a clearsolution. Diethyl azodicarboxylate (6.98 mL, 44.36 mmol) was addeddropwise to the reaction mixture. The rate of addition was maintainedsuch that resulting deep red coloration is just discharged before addingthe next drop. After the addition was complete, the reaction was stirredfor 4 h. By that time TLC showed the completion of the reaction (ethylacetate/hexane, 60:40). The solvent was evaporated under vacuum. Residueobtained was placed on a flash silica gel column and eluted with ethylacetate-hexane (60:40) to give the title compound as a white foam(21.8.g).

¹H NMR (DMSO-d₆): δ 11.32 (s, 1H), 7.82 (m, 4H), 7.6-7.65 (m, 5H),7.34-7.46 (m, 6H), 5.90 (d, 1H, J=6Hz), 5.18 (d, J=5.6 Hz), 4.31 (bs,2H), 4.25 (m, 1H), 4.09 (t, 1H, J=5.6 Hz), 3.81-3.94 (m, 5H), 1.44 (s,3H), 1.1 (s, 9H); ¹³C NMR (CDCl₃): δ 11.8, 19.40, 26.99, 62.62, 68.36,68.56, 77.64, 83.04, 84.14, 87.50, 110.93, 123.59, 127.86, 129.89,132.45, 134.59, 134.89, 135.17, 150.50, 163.63, 163.97; MS [FAB] m/z 684[M−H]⁻.

Step C:5′-O-tert-Butyldiphenylsilyl-2′-O-[2-(acetaldoximinooxy)ethyl]-5-methyluridine

2′-O-[2-(2-Phthalimidoxy)ethyl]-5′-t-butyldiphenylsilyl-5-methyluridine(10 g, 14.6 mmol) was dissolved in CH₂Cl₂ (146 mL) and cooled to −10° C.in an isopropanol-dry ice bath. To this methylhydrazine (1.03 mL, 14.6mmol) was added dropwise. Reaction mixture was stirred at −10° C. to 0°C. for 1 h. A white precipitate formed and was filtered and washedthoroughly with CH₂Cl₂ (ice cold). The filtrate was evaporated todryness. Residue was dissolved in methanol (210 mL) and acetaldehyde(0.89 mL, 16 mmol) was added and stirred at room temperature for 12 h.Solvent was removed in vacuo and residue was purified by silica gelcolumn chromatography using and ethyl acetate/hexane (6:4) as solventsystem to yield the title compound (4.64 g).

¹H NMR (DMSO-d₆): δ 1.02 (s, 9H), 1.44 (s, 3H), 1.69 (dd, 3H, J=5.6 Hz),3.66 (m, 1H), 3.76 (m, 2H), 3.94 (m, 2H), 4.05 (s, 2H), 4.15 (m, 1H),4.22 (m, 1H), 5.18 (d, 1H, J=6.0 Hz), 5.9 (dd, 1H, J=4.4 Hz), 7.36 (m,1H), 7.40 (m, 7H), 7.63 (m, 5H), 11.38 (s, 1H), ¹³C NMR (CDCl₃): δ11.84, 15.05, 19.38, 26.97, 63.02, 68.62, 70.26, 71.98, 72.14, 82.72,84.34, 87.02, 111.07, 127.89, 130.02, 134.98, 135.13, 135.42, 147.85,150.51, 164.12; HRMS (FAB) Calcd for C₃₀H₃₉N₃O₇ SiNa^(⊕) 604.2455, found604.2471.

Step D: 5′-O-tert-Butyldiphenylsilyl-2′-O-[2-(NN-diethylaminooxy)ethyl]-5-methyluridine

5′-O-tert-Butyldiphenylsilyl-2′-O-[2-(acetaldoximinooxy)ethyl]-5-methyluridine(4.5 g, 7.74 mmol) was dissolved in 1M pyridinium p-toluenesulfonate(PPTS) in MeOH (77.4 mL). It was then cooled to 10° C. in an ice bath.To this mixture NaBH₃CN (0.97 g, 15.5 mmol) was added and the mixturewas stirred at 10° C. for 10 minutes. Reaction mixture was allowed tocome to room temperature and stirred for 4 h. Solvent was removed invacuo to give an oil. Diluted the oil with ethyl acetate (100 mL),washed with water (75 mL), 5% NaHCO₃ (75 mL) and brine (75 mL). Theorganic phase was dried over anhydrous Na₂SO₄ and evaporated. Residueobtained was dissolved in 1M PPTS in MeOH (77.4 mL), acetaldehyde (0.48mL, 8.52 mmol) was added and stirred at ambient temperature for 10minutes. Then reaction mixture was cooled to 10° C. in an ice bath andNaBH₃CN (0.97 g, 15.50 mmol) was added and stirred at 10° C. for 10minutes. Reaction mixture was allowed to come to room temperature andstirred for 4 h. Solvent was removed in vacuo to get an oil. The oil wasdissolved in ethyl acetate (100 mL), washed with water (75 mL), 5%NaHCO₃ (75 mL) and brine (75 mL). The organic phase was dried overanhydrous Na₂SO₄ and evaporated to dryness. The residue obtained waspurified by silica gel column chromatography and eluted with CH₂Cl₂/MeOH/NEt₃, 94:5:1 to give title compound (3.55 g) as a white foam.

¹H NMR (DMSO-d₆): δ 0.95 (t, 6H, J=7.2 Hz), 1.03 (s, 9H), 1.43 (s, 3H),2.58 (q, 4H, J=7.2 Hz), 3.59 (m, 1H), 3.73 (m, 3H), 3.81 (m, 1H), 3.88(m, 1H), 3.96 (m, 2H), 4.23 (m, 1H), 5.21 (d, 1H, J=5.6 Hz), 5.95 (d,1H, J=6.4 Hz), 7.43 (m, 7H), 7.76 (m, 4H), 11.39 (s, 1H); ¹³C NMR(CDCl₃): δ 11.84, 19.35, 26.97, 52.27, 63.27, 68.81, 70.27, 72.27,82.64, 84.47, 86.77, 111.04, 127.87, 130.01, 135.11, 135.41, 141.32,150.48, 164.04; HRMS (FAB), Calcd for C₃₂H₄₅N₃O₇SiCs^(⊕), 744.2081,found 744.2067.

Step E: 2′-O-[2-(N,N-diethylaminooxy)ethyl]-5-methyluridine

A mixture of triethlyamine trihydrogenfluoride (4.39 mL, 26.81 mmol) andtriethylamine (1.87 mL, 13.41 mmol) in THF (53.6 mL) was added to5′-O-tert-butyldiphenylsilyl-2′-O-[2-(N,N-diethylaminooxy)ethyl]-5-methyluridine(3.28 g, 5.36 mmol). The reaction mixture was stirred at roomtemperature for 18 h. Solvent was removed in vacuo. The residue wasplaced on a silica gel column and eluted with CH₂Cl₂/MeOH/NEt₃, 89: 10:1, to yield the title compound (1.49 g).

¹H NMR (DMSO-d₆): δ 0.97 (t, 6H, J=7.2 Hz), 1.75 (s, 3H), 2.58 (q, 4H,J=7.2 Hz), 3.55 (m, 4H), 3.66 (m, 2H), 3.83 (bs, 1H), 3.95 (t, 1H, J=5.6Hz), 4.11 (q, 1H, J=4.8 Hz and 5.6 Hz), 5.05 (d, 1H, J=5.6 Hz), 5.87 (d,1H, J=6.0 Hz), 7.75 (s, 1H), 11.31 (s, 1H); ¹³C NMR (CDCl₃): 5 11.75,12.27, 52.24, 61.31, 68.86, 70.19, 72.25, 81.49, 85.10, 90.29, 110.60,137.79, 150.57, 164.37; HRMS (FAB) Calcd for C₁₆H₂₈N₃O₇ ^(⊕) 374.1927,found 374.1919.

EXAMPLE 103 1-(2-C-Methyl-β-D-arabinofuranosyl)uracil

This compound was prepared following the procedures described in Chem.Pharm. Bull. 35: 2605 (1987).

EXAMPLE 104 5-Methyl-3′-deoxycytidine

This compound was prepared following the procedures described in Chem.Pharm. Bull. 30: 2223 (1982).

EXAMPLE 105 2-Amino-2′-O-methyladenosine

This compound was obtained from commercial sources.

EXAMPLE 106 2′-Deoxy-2′-fluoroadenosine

This compound was obtained from commercial sources.

EXAMPLE 107 3′-Deoxy-3′-fluoroadenosine

This compound was prepared following the procedures described inNucleosides Nucleotides 10: 719 (1991).

EXAMPLE 108 3′-Deoxy-3′-methyladenosine

This compound was prepared following the procedures described in J. Med.Chem. 19: 1265 (1976).

EXAMPLE 1092-Amino-7-(2-deoxy-β-D-ribofuranosyl)-7H-pyrrolo[2.3-d]pyrimidine

This compound was prepared following the procedures described in J. Am.Chem. Soc. 106: 6379 (1984).

EXAMPLE 110 4-Amino-7-(β-D-arabinofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine

This compound is described in U.S. Pat. No. 4,439,604, which isincorporated by reference herein in its entirety.

EXAMPLE 1114-Amino-1-(3-deoxy-3-fluoro-β-D-ribofuranosyl)-1H-imidazo[4,5-c]pyridine

This compound can be prepared readily by the similar method describedfor the preparation of Example 24 except the nucleobase is3-deazaadenine.

EXAMPLE 112 4-Amino-7-(β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine(tubercidin)

This compound was obtained from commercial sources.

EXAMPLE 1134-Amino-1-(3-deoxy-β-D-ribofuranosyl)-1H-imidazo[4,5-c]pyridine

This compound is described in Acta Crystallogr., Sect. C: Cryst. Struct.Commun. C43: 1790 (1987).

EXAMPLE 1144-Amino-1-(3-deoxy-3-methyl-β-D-ribofuranosyl)-1H-imidazo[4,5-c]pyridine

The procedure described earlier for Example 23 is used to synthesizethis example by reacting the appropriately substituted 3-C-methyl-sugarintermediate with a protected 3-deazaadenine derivative.

EXAMPLE 115 4-Amino-1-β-D-ribofuranosyl-1H-imidazo[4,5-c]pyridine

This compound was obtained from commercial sources.

EXAMPLE 116 9-(2-C-Methyl-β-D-arabinofuranosyl)adenine

This compound is prepared from4-amino-9-(3,5-bis-O-tert-butyldimethylsilyl-β-D-erythro-pentofuran-2-ulosyl)purine(J. Med. Chem. 1992, 35, 2283) by reaction with MeMgBr and deprotectionas described in Example 61.

EXAMPLE 1174-Amino-7-(2-C-ethyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine

Step A:3,5-Bis-O-(2,4-dichlorophenylmethyl)-2-C-ethyl-1-O-methyl-α-D-ribofuranose

To diethyl ether (300 mL) at −78° C. was slowly added EtMgBr (3.0 M,16.6 mL) and then dropwise the compound from Step B of Example 62 (4.80g, 10.0 mmol) in anhydrous Et₂O (100 mL). The reaction mixture wasstirred at −78° C. for 15 min, allowed to warm to −15° C. and stirredfor another 2 h, and then poured into a stirred mixture of water (300mL) and Et₂O (600 mL). The organic phase was separated, dried (MgSO4),and evaporated in vacuo. The crude product was purified on silica gelusing ethyl acetate/hexane (1:2) as eluent. Fractions containing theproduct were pooled and evaporated in vacuo to give the desired product(3.87 g) as a colorless oil.

Step B:4-Chloro-7-[3,5-bis-O-(2,4-dichlorophenylmethyl)-2-C-ethyl-β-D-ribofuranosyl]-7H-pyrrolo[2,3-d]pyrimidine

To a solution of the compound from Step A (1.02 mg, 2.0 mmol) indichloromethane (40 mL) was added HBr (5.7 M in acetic acid) (1.75 mL,10.0 mmol) dropwise at 0° C. The resulting solution was stirred at rtfor 2 h, evaporated in vacuo and co-evaporated twice from toluene (10mL). The oily residue was dissolved in acetonitrile (10 mL) and added toa vigorously stirred mixture of 4-chloro-1H-pyrrolo[2,3-d]pyrimidine(307 mg, 2.0 mmol), potassium hydroxide (337 mg, 6.0 mmol) andtris[2-(2-methoxyethoxy)ethyl]amine (130 mg, 0.4 mmol) in acetonitrile(10 mL). The resulting mixture was stirred at room temperatureovernight, and then poured into a stirred mixture of saturated ammoniumchloride (100 mL) and ethyl acetate (100 mL). The organic layer wasseparated, washed with brine (100 mL), dried over MgSO₄, filtered andevaporated in vacuo. The crude product was purified on silica gel usingethyl acetate/hexane (1:2) as eluent to give the desired product (307mg) as a colorless foam.

Step C:4-Chloro-7-(2-C-ethyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine

To a solution of the compound from Step B (307 mg, 0.45 mmol) indichloromethane (8 mL) was added boron trichloride (1M indichloromethane) (4.50 mL, 4.50 mmol) at −78° C. The mixture was stirredat −78° C. for 1 h, then at −10° C. for 3 h. The reaction was quenchedby addition of methanol/dichloromethane (1:1) (10 mL), stirred at −15°C. for 30 min, and neutralized by addition of aqueous ammoniumhydroxide. The mixture was evaporated in vacuo and the resulting oilpurified on silica gel using methanol/dichloromethane (1:9) as eluent.Fractions containing the product were pooled and evaporated in vacuo togive the desired product (112 mg) as a colorless foam.

Step D:4-Amino-7-(2-C-ethyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine

To the compound from Step C (50 mg, 0.16 mmol) was added saturatedammonia in methanol (4 mL). The mixture was stirred at 75° C. for 72 hin a closed container, cooled and evaporated in vacuo. The crude mixturewas purified on silica gel using methanol/dichloromethane (1:9) aseluent. Fractions containing the product were pooled and evaporated invacuo to give the desired product (29 mg) as a colorless powder.

¹H NMR (200 MHz, DMSO-d₆): δ 0.52 (t, 3H), 1.02 (m, 2H), 4.01-3.24 (m,6H), 5.06 (m, 1H), 6.01 (s, 1H), 6.51 (d, 1H), 6.95 (s br, 2H), 6.70 (d,1H), 7.99 (s, 1H).

LC-MS: Found: 295.2 (M+H⁺); calc. for C₁₃H₁₈N₄O₄+H⁺: 295.14.

EXAMPLE 1182-Amino-7-(2-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-one

Step A:2-Amino-4-chloro-7-[3,5-bis-O-(2,4-dichlorophenylmethyl)-2-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine

To an ice-cold solution of product from Step C of Example 62 (1.27 g,2.57 mmol) in CH₂Cl₂ (30 mL) was added HBr (5.7 M in acetic acid; 3 mL)dropwise. The reaction mixture was stirred at room temperature for 2 h,concentrated in vacuo and co-evaporated with toluene (2×15 mL). Theresulting oil was dissolved in MeCN (15 mL) and added dropwise into awell-stirred mixture of 2-amino-4-chloro-7H-pyrrolo[2,3-d]pyrimidine[for preparation see Heterocycles 35: 825 (1993)] (433 mg, 2.57 mmol),KOH (85%, powdered) (0.51 g, 7.7 mmol),tris-[2-(2-methoxyethoxy)ethyl]amine (165 μL, 0.51 mmol) in acetonitrile(30 mL). The resulting mixture was stirred at rt for 1 h, filtered andevaporated. The residue was purified on a silica gel column usinghexanes/EtOAc, 5/1, 3/1 and 2/1 as eluent to give the title compound asa colorless foam (0.65 g).

Step B: 2-Aminochloro-7-(2-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine

To a solution of the product from Step A (630 mg, 1.0 mmol) in CH₂Cl₂(20 mL) at −78° C. was added boron trichloride (1M in CH₂Cl₂) (10 mL, 10mmol). The mixture was stirred at −78° C. for 2 h, then at −20° C. for2.5 h. The reaction was quenched with CH₂Cl₂/MeOH (1:1) (10 mL), stirredat −20° C. for 0.5 h, and neutralized at 0° C. with aqueous ammonia. Thesolid was filtered, washed with CH₂Cl₂/MeOH (1:1) and the combinedfiltrate evaporated in vacuo. The residue was purified on a silica gelcolumn with CH₂Cl₂/MeOH, 50/1 and 20/1 as eluent to give the titlecompound as a colorless foam (250 mg).

Step C:2-Amino-7-(2-C-methyl-β-D-ribofiuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-one

A mixture of product from Step B (90 mg, 0.3 mmol) in aqueous NaOH (2N,9 mL) was heated at reflux temperature for 5 h, then neutralized at 0°C. with 2 N aqueous HCl and evaporated to dryness. Purification on asilica gel column with CH₂Cl₂/MeOH, 5/1 as eluent afforded the titlecompound as a white solid (70 mg).

¹H NMR (200 MHz, CD₃OD): δ 0.86 (s, 3H), 3.79 (m 1H), 3.90-4.05 (m, 3H),6.06 (s, 1H), 6.42 (d, J=3.7 Hz, 1H), 7.05 (d, J=3.7 Hz, 1H).

EXAMPLE 1192-Amino-4-cyclopropylamino-7-(2-C-methyl-β-D-ribofiuranosyl)-7H-pyrrolo[2,3-d]pyrimidine

A solution of2-amino-4-chloro-7-(2-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine(Example 118, Step B) (21 mg, 0.07 mmol) in cyclopropylamine (0.5 mL)was heated at 70° C. for two days, then evaporated to an oily residueand purified on a silica gel column with CH₂Cl₂/MeOH, 20/1, as eluent togive the title compound as a white solid (17 mg).

¹H NMR (200 MHz, CD₃CN): δ 0.61 (m, 2H), 0.81 (m, 2H), 0.85 (s, 3H),2.83 (m, 1H), 3.74-3.86 (m, 1H), 3.93-4.03 (m, 2H), 4.11 (d, J=8.9 Hz,1H), 6.02 (s, 1H), 6.49 (d, J=3.7 Hz, 1H), 7.00 (d, J=3.7 Hz, 1H).

EXAMPLE 120 3′,5′-Bis-[O-(1-oxooctyl)]-2′-O-methylcytidine

1,3-Dicyclohexylcarbodiimide (21.48 g, 104 mmol) was dissolved inanhydrous dichloromethane (100 mL). To the solution was added octanoicacid (5.49 mL, 34.5 mmol, made anhydrous by keeping over molecularsieves, 4 Å overnight at room temperature), and the resulting reactionmixture was stirred under argon atmosphere for 6 h. The whiteprecipitate which formed was filtered, and the filtrate was concentratedunder reduced pressure. The residue obtained was dissolved in anhydrouspyridine and added to N⁴-(4,4′-dimethoxytrityl)-2′-O-methylcytidine(0.43 g, 0.77). DMAP (0.09 g, 0.77 mmol) was added and the resultingmixture was stirred at room temperature under argon atmosphere for 12 h.The solvent was removed under reduced pressure and the residue obtainedwas dissolved in ethyl acetate (100 mL). The organic phase was washedwith aqueous sodium bicarbonate (5%, 50 mL), dried over anhydrousNa₂SO₄and concentrated under reduced pressure. The residue was purifiedby flash silica gel column chromatography and eluted with 5% MeOH indichloromethane. The product obtained was dissolved in a mixture ofacetic acid: MeOH:H2O (20 mL, 3:6:1). The resulting mixture was heatedat 50° C. for 24 h. The solvent was removed under reduced pressure. Theresidue obtained was purified by flash silica gel column chromatographyand eluted with dichloromethane containing 0 to 5% of MeOH to give thetitle compound (0.22.g).

¹H NMR (200 MHz, DMSO-d₆) δ 0.83 (m, 611), 1.23 (br s, 16H), 1.51 (m,4H), 2.33 (m, 4H), 3.26 (s, 31), 4.06 (t, J=5.2 Hz, 1H), 4.21 (m, 31),5.11 (t, J=5.2 Hz, 1H), 5.75 (d, J3=7.4 Hz, 1H), 5.84 (d, J3=4.8 Hz,1H), 7.26 (br s, 2H), 7.61 (d, J=7.4 Hz, 1H). MS (ES): m/z 510.3 [M+H]⁺;HRMS (FAB) Calcd for C₂₆H₄₄N₃O₇: 510.3179; found 510.3170.

EXAMPLE 121 4-Amino-1-(β-D-ribofuranosyl)-1H-pyrazolo[3,4-d]pyrimidine

This compound was prepared following procedures described in NucleicAcids Res., 11: 871-872 (1983).

EXAMPLE 122 2′ C-Methyl-cytidine

This compound was prepared following procedures described in L.Beigelman et al., Carbohyd. Res. 166: 219-232 (1987) or X-Q Tang, etal., J. Org. Chem. 64: 747-754 (1999).

EXAMPLE 1234-Amino-7-(2-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine-5-carbonitrile

This compound was prepared following procedures described by Y. Murai etal. in Heterocycles 33: 391-404 (1992).

EXAMPLE 1244-Amino-7-(2-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyridine-5-carboxamide

This compound was prepared following procedures described by Y. Murai etal. in Heterocycles 33: 391-404 (1992).

EXAMPLE 125 8-Aminoadenosine

This compound was prepared following the procedure described in M.Ikehara and S. Yamada, Chem. Pharm. Bull., 19: 104 (1971).

EXAMPLE 126 Mass Spectral Characterization of Nucleoside5′-Triphosphates

Mass spectra of nucleoside 5′-triphosphates were determined as describedin Example 87. Listed in the following table are the calculated andexperimental masses for the nucleoside 5′-triphosphates preparedaccording to the procedures of Example 86. The example numberscorrespond to the parent nucleoside of the nucleoside 5′-triphosphate.

Example Calculated Found 1 507.0 506.9 2 525.0 524.9 5 537.0 537.0 6539.0 539.0 7 565.0 565.0 8 547.0 546.9 9 550.0 550.0 10 506.0 505.9 11536.0 535.9 12 536.0 536.0 13 561.0 560.9 14 550.0 550.0 15 524.0 524.016 522.0 521.9 17 547.0 546.9 18 536.0 536.0 20 531.0 530.9 21 522.0522.0 22 536.0 536.0 23 506.0 506.1 24 524.0 524.0 25 508.0 508.0 26508.0 508.0 27 552.0 552.0 28 506.0 506.0 29 579.0 578.9 30 582.0 582.031 568.0 567.9 32 554.0 553.9 33 540.0 539.9 34 554.0 553.9 35 568.0567.9 36 541.0 541.0 37 565.0 564.9 38 542.0 541.9 39 554.0 553.9 41481.0 481.0 42 467.0 467.0 43 485.0 484.8 46 482.0 482.0 47 486.0 485.848 482.0 482.0 49 554.0 554.0 51 468.0 468.1 52 521.0 521.0 53 491.0491.2 55 584.9 585.1 56 521.0 521.2 58 506.0 506.0 61 520.0 519.9 62520.0 520.0 63 547.0 547.0 64 533.0 533.0 65 549.0 549.0 67 551.0 551.068 515.0 514.9 69 520.0 520.1 71 490.0 489.9 89 523.0 522.9 90 521.0520.9 91 645.1 645.0 94 524.0 523.9 95 522.0 521.8 98 536.0 535.9 99520.0 520.0 102 613.1 613.0 103 498.0 497.9 104 481.0 481.0 105 536.0536.2 106 509.0 508.9 108 505.0 505.0 112 506.0 506.1 113 490.0 490.0117 534.0 534.0 118 536.0 536.0

EXAMPLE 127[4-Amino-7-(2-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]-pyrimidine]-5′-monophosphate

To the compound from Step F of Example 62 (14 mg, 0.05 mmol) (dried bycoevaporation with pyridine and several times with toluene) was addedtrimethyl phosphate (0.5 mL). The mixture was stirred- overnight in asealed container. It was then cooled to 0° C. and phosphorousoxychloride (0.0070 mL, 0.075 mmol) was added via a syringe. The mixturewas stirred for 3 h at 0° C., then the reaction was quenched by additionof tetraethylammonium bicarbonate (TEAB) (1M) (0.5 mL) and water (5 mL).The reaction mixture was purified and analyzed according to theprocedure described in Example 87.

Electron spray mass spectrum (ES-MS): Found: 359.2 (M−H⁺), calc. forC₁₂H₁₇N₄O₇P−H⁺: 359.1.

EXAMPLE 128[4-Amino-7-(2-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]-pyrimidine]-5′-diphosphate

To the compound from Step F of Example 62 (56 mg, 0.20 mmol) (dried bycoevaporation with pyridine and several times with toluene) was addedtrimethyl phosphate (stored over sieves) (1.0 mL). The mixture wasstirred overnight in a sealed container. It was then cooled to 0° C. andphosphorous oxychloride (0.023 mL, 0.25 mmol) was added via a syringe.The mixture was stirred for 2 h at 0° C., then tributylamine (0.238 mL,1.00 mmol) and tributylammonium phosphate (generated from phosphoricacid and tributylamine in pyridine, followed by repeated azeotropicevaporation with pyridine and acetonitrile) (1.0 mmol in 3.30 mLacetonitrile) was added. The mixture was stirred for an additional 30min at 0° C., the sealed vial was then opened and the reaction quenchedby addition of TEAB (1M) (1.0 mL) and water (5 mL). The reaction mixturewas purified and analyzed according to the procedure described inExample 87.

ES-MS: Found: 439.0 (M−H⁺), calc. for C₁₂H₁₈N₄O₁₀P₂−H⁺: 439.04.

EXAMPLE 129[4-Amino-7-(2-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]-pyrimidine]-5′-triphosphate

To the compound from Step F of Example 62 (20 mg, 0.07 mmol) (dried bycoevaporation with pyridine and several times with toluene) was addedtrimethyl phosphate (stored over sieves) (0.4 mL). The mixture wasstirred overnight in a sealed container. It was then cooled to 0° C. andphosphorous oxychloride (0.0070 mL, 0.075 mmol) was added via syringe.The mixture was stirred for 3 h at 0° C., then tributylamine (0.083 mL,0.35 mmol), tributylammonium pyrophosphate (0.35 mmol, 127 mg) andacetonitrile (stored over sieves) (0.25 mL) were added. The mixture wasstirred for an additional 30 min at 0° C., the sealed vial was thenopened and the reaction quenched by addition of TEAB (1M) (0.5 mL) andwater (5 mL). The reaction mixture was purified and analyzed accordingto the procedure described in Example 87.

ES-MS: Found: 519.0 (M−H⁺), calc. for C₁₂H₁₉N₄O₁₃P₃−H⁺: 519.01.

EXAMPLE 1307-(2-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-one

To the compound from Step E of Example 62 (59 mg, 0.18 mmol) was addedaqueous sodium hydroxide (1M). The mixture was heated to reflux for 1hr, cooled, neutralized with aqueous HCl (2M) and evaporated in vacuo.The residue was purified on silica gel using dichloromethane/methanol(4:1) as eluent. Fractions containing the product were pooled andevaporated in vacuo to give the desired product (53 mg) as a colorlessoil.

¹H NMR (CD₃CN): δ 0.70 (s, 3H), 3.34-4.15 (overlapping m, 7H), 6.16 (s,1H), 6.57 (d, 3.6 Hz, 1H), 7.37 (d, 3.6 Hz, 1H), 8.83 (s, 1H).

EXAMPLE 1314-Amino-5-chloro-7-(2-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine

To a pre-cooled solution (0° C.) of the compound from Step F of Example62 (140 mg, 0.50 mmol) in DMF (2.5 mL) was added N-chlorosuccinimide(0.075 g, 0.55 mmol) in DMF (0.5 mL) dropwise. The solution was stirredat rt for 1 h and the reaction quenched by addition of methanol (4 mL)and evaporated in vacuo. The crude product was purified on silica gelusing methanol/dichloromethane (1:9) as eluent. Fractions containing theproduct were pooled and evaporated in vacuo to give the desired product(55 mg) as a colorless solid.

¹H NMR (CD₃CN): δ 0.80 (s, 3H), 3.65-4.14 (overlapping m, 7H), 5.97 (sbr, 2H), 6.17 (s, 1H), 7.51 (s, 1H), 8.16 (s, 1H).

ES-MS: Found: 315.0 (M+H⁺), calc.for C₁₂H₁₅ClN₄O₄+H⁺: 315.09.

EXAMPLE 1324-Amino-5-bromo-7-(2-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine

To a pre-cooled solution (0° C.) of the compound from Step F of Example62 (28 mg, 0.10 mmol) in DMF (0.5 mL) was added N-bromosuccinimide(0.018 g, 0.10 mmol) in DMF (0.5 mL) dropwise. The solution was stirredat 0° C. for 20 min, then at rt for 10 min. The reaction was quenched byaddition of methanol (4 mL) and evaporated in vacuo. The crude productwas purified on silica gel using methanol/dichloromethane (1:9) aseluent. Fractions containing the product were pooled and evaporated invacuo to give the desired product (13.0 mg) as a colorless solid.

¹H NMR (CD₃CN): δ 0.69 (s, 3H), 3.46-4.00 (overlapping m, 7H), 5.83 (sbr, 2H), 6.06 (s, 1H), 7.45 (s, 1H), 8.05 (s, 1H).

ES-MS: Found: 359.1 (M+H⁺), calc. for C₁₂H₁₅BrN₄O₄+H⁺: 359.04.

EXAMPLE 1332-Amino-7-(2-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine

A mixture of2-amino-4-chloro-7-(2-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine(Example 118, Step B) (20 mg, 0.07 mmol) in EtOH (1.0 mL), pyridine (0.1mL) and 10% Pd/C (6 mg) under H₂ (atmospheric pressure) was stirredovernight at room temperature. The mixture was filtered through a Celitepad which was thoroughly washed with EtOH. The combined filtrate wasevaporated and purified on a silica gel column with CH₂Cl₂/MeOH, 20/1and 10/1, as eluent to give the title compound as a white solid (16 mg).

¹H NMR (200 MHz, CD₃OD): δ 0.86 (s, 3H, 2′C-Me), 3.82 (dd, J_(5′4′)=3.6Hz, J_(5′,5″)=12.7 Hz, 1H, H-5′), 3.94-4.03 (m, 2H, H-5′, H4′), 4.10 (d,J_(3′4′)=8.8 Hz, 1H, H-3′), 6.02 (s, 1H, H-1′), 6.41 (d, J_(5,6)=3.8 Hz,1H, H-5), 7.39 (d, 1H, H-6), 8.43 (s, 1H, H-4). ES MS: 281.4 (MH⁺).

EXAMPLE 1342-Amino-5-methyl-7-(2-C,2-O-dimethyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-one

Step A:2-Amino-4-chloro-7-[3,5-bis-O-(2,4-dichlorophenylmethyl)-2-C-methyl-β-D-ribofuranosy]-5-methyl-7H-pyrrolo[2,3-d]pyrimidine

To an ice-cold solution of the product from Step C of Example 62 (1.57g, 3.16 mmol) in CH₂Cl₂ (50 mL) was added HBr (5.7 M in acetic acid; 3.3mL) dropwise. The reaction mixture was stirred at 0° C. for 1 h and thenat room temperature for 2 h, concentrated in vacuo and co-evaporatedwith toluene (2×20 mL). The resulting oil was dissolved in MeCN (20 mL)and added dropwise to a solution of the sodium salt of2-amino-4-chloro-5-methyl-1H-pyrrolo[2,3-d]pyrimidine in acetonitrile[generated in situ from2-amino-4-chloro-5-methyl-1H-pyrrolo[2,3-d]pyrimidine [for preparation,see Liebigs Ann. Chem. 1984: 708-721] (1.13 g, 6.2 mmol) in anhydrousacetonitrile (150 mL), and NaH (60% in mineral oil, 248 mg, 6.2 mmol),after 2 h of vigorous stirring at rt]. The combined mixture was stirredat rt for 24 h and then evaporated to dryness. The residue was suspendedin water (100 mL) and extracted with EtOAc (300+150 mL). The combinedextracts were washed with brine (100 mL), dried over Na₂SO₄, filteredand evaporated. The crude product was purified on a silica gel column(5×7 cm) using ethyl acetate/hexane (0 to 30% EtOAc in 5% step gradient)as the eluent. Fractions containing the product were combined andevaporated in vacuo to give the desired product (0.96 g) as a colorlessfoam.

Step B:2-Amino-4-chloro-7-[3,5-bis-O-(2,4-dichlorophenylmethyl)-2-C,2-O-dimethyl-β-D-ribofuranosyl]-5-methyl-7H-pyrrolo[2,3-d]pyrimidine

To an ice-cold mixture of the product from Step A (475 mg, 0.7 mmol) inTHF (7 mL) was added NaH (60% in mineral oil, 29 mg) and stirred at 0°C. for 0.5 h. Then MeI (48 μL) was added and reaction mixture stirred atrt for 24 h. The reaction was quenched with MeOH and the mixtureevaporated. The crude product was purified on a silica gel column (5×3.5cm) using hexane/ethyl acetate (9/1, 7/1, 5/1 and 3/1) as eluent.Fractions containing the product were combined and evaporated to givethe desired compound (200 mg) as a colorless foam.

Step C:2-Amino-7-[3,5-bis-O-(2,4-dichlorophenylmethyl)-2-C,2-O-dimethyl-β-D-ribofuranosyl]-5-methyl-7H-pyrrolo[2,3-d]pyrimidine-4(3H)-one

A mixture of the product from Step B (200 mg, 0.3 mmol) in 1,4-dioxane(15 mL) and aqueous NaOH (2N, 15 mL) in a pressure bottle was heatedovernight at 135° C. The mixture was then cooled to 0° C., neutralizedwith 2N aqueous HCl and evaporated to dryness. The crude product wassuspended in MeOH, filtered, and the solid thoroughly washed with MeOH.The combined filtrate was concentrated, and the residue purified on asilica gel column (5×5 cm) using CH₂Cl₂/MeOH (40/1, 30/1 and 20/1) aseluent to give the desired compound (150 mg) as a colorless foam.

Step D:2-Amino-5-methyl-7-(2-C,2-O-dimethyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-one

A mixture of the product from Step C (64 mg, 0.1 mmol) in MeOH (5 mL)and Et₃N (0.2 mL) and 10% Pd/C (24 mg) was hydrogenated on a Parrhydrogenator at 50 psi at r.t. for 1.5 days, then filtered through aCelite pad which was thoroughly washed with MeOH. The combined filtratewas evaporated and the residue purified on a silica gel column (3×4 cm)with CH₂Cl₂/MeOH (30/1, 20/1) as eluent to yield2-amino-5-methyl-7-(5-O-benzyl-2-C,2-O-dimethyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-one.The compound (37 mg) was further hydrogenated in EtOH (2 mL) with 10%Pd/C and under atmospheric pressure of hydrogen. After stirring 2 daysat r.t., the reaction mixture was filtered through Celite, the filtrateevaporated and the crude product purified on a silica gel column (1×7cm) with CH₂Cl₂/MeOH (30/1, 20/1 and 10/1) as eluent to yield the titlecompound (12 mg) after freeze-drying.

¹H NMR (200 MHz, CD₃OD): δ 0.81 (s, 3H, 2′C-Me), 2.16 (d,J_(H-6,C5-Me)=1.3 Hz, 3H, C5-Me), 3.41 (s, 3H, 2′-OMe), 3.67 (dd,J_(5′4)′=3.4 Hz, J_(5′,5″)=12.6 Hz, 1H, H-5′), 3.81-3.91 (m, 3H, H-5″,H-4′, H-3′), 6.10 (s, 1H, H-1′), 6.66 (d, 1H, H-6).

ES MS: 323.3 (M−H)⁺.

EXAMPLE 1354-Amino-5-methyl-7-(2-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine

Step A:4-Chloro-7-[3,5-bis-O-(2,4-dichlorophenylmethyl)-2-C-methyl-β-D-ribofuranosyl]-5-methyl-7H-pyrrolo[2,3-d]pyrimidine

To an ice-cold solution of the product from Step C of Example 62 (1.06g, 2.1 mmol) in CH₂Cl₂ (30 mL) was added HBr (5.7 M in acetic acid; 2.2mL) dropwise. The reaction mixture was stirred at 0° C. for 1 h and thenat room temperature for 2 h, concentrated in vacuo and co-evaporatedwith toluene (2×15 mL). The resulting oil was dissolved in MeCN (10 mL)and added dropwise into a solution of the sodium salt of4-chloro-5-methyl-1H-pyrrolo[2,3-d]pyrimidine in acetonitrile [generatedin situ from 4-chloro-5-methyl-1H-pyrrolo[2,3-d]pyrimidine [forpreparation, see J. Med. Chem. 33: 1984 (1990)] (0.62 g, 3.7 mmol) inanhydrous acetonitrile (70 mL), and NaH (60% in mineral oil, 148 mg, 3.7mmol), after 2 h of vigorous stirring at rt]. The combined mixture wasstirred at rt for 24 h and then evaporated to dryness. The residue wassuspended in water (100 mL) and extracted with EtOAc (250+100 mL). Thecombined extracts were washed with brine (50 mL), dried over Na₂SO₄,filtered and evaporated. The crude product was purified on a silica gelcolumn (5×5 cm) using hexane/ethyl acetate (9/1, 5/1, 3/1) gradient asthe eluent. Fractions containing the product were combined andevaporated in vacuo to give the desired product (0.87 g) as a colorlessfoam.

Step B:4-Chloro-5-methyl-7-(2-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine

To a solution of the compound from Step A (0.87 g, 0.9 mmol) indichloromethane (30 mL) at −78° C. was added boron trichloride (1M indichloromethane, 9.0 mL, 9.0 mmol) dropwise. The mixture was stirred at−78° C. for 2.5 h, then at −30° C. to −20° C. for 3 h. The reaction wasquenched by addition of methanol/dichloromethane (1:1) (9 mL) and theresulting mixture stirred at −15° C. for 30 min., then neutralized withaqueous ammonia at 0° C. and stirred at rt for 15 min. The solid wasfiltered and washed with CH₂Cl₂/MeOH (1/1, 50 mL). The combined filtratewas evaporated, and the residue was purified on a silica gel column (5×5cm) using CH₂Cl₂ and CH₂Cl₂/MeOH (40/1 and 30/1) gradient as the eluentto furnish the desired compound (0.22 g) as a colorless foam.

Step C:4-Amino-5-methyl-7-(2-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine

To the compound from Step B (0.2 g, 0.64 mmol) was added methanolicammonia (saturated at 0° C.; 40 mL). The mixture was heated in astainless steel autoclave at 100° C. for 14 h, then cooled andevaporated in vacuo. The crude mixture was purified on a silica gelcolumn (5×5 cm) with CH₂Cl₂/MeOH (50/1, 30/1, 20/1) gradient as eluentto give the title compound as a white solid (0.12 g).

¹H NMR (DMSO-d₆): δ 0.60 (s, 3H, 2′C-Me), 2.26 (s, 3H, 5C-Me), 3.52-3.61(m, 1H, H-5′), 3.70-3.88 (m, 3H, H-5″, H4′, H-3′), 5.00 (s, 1H, 2′-OH),4.91-4.99 (m, 3H, 2′-OH, 3′-OH, 5′-OH), 6.04 (s, 1H, H-1′), 6.48 (br s,2H, NH2), 7.12 (s, 1H, H-6), 7.94 (s, 1H, H-2). ES MS: 295.2 (MH⁺).

EXAMPLE 1364-Amino-7-(2-C-methyl-β-D-ribofiuranosyl)-7H-pyrrolo[2,3-d]pyrimidine-5-carboxylicAcid

The compound of Example 123 (0.035 g, 0.11 mmol) was dissolved in amixture of aqueous ammonia (4 mL, 30 wt %) and saturated methanolicammonia (2 mL), and a solution of H₂O₂ in water (2 mL, 35 wt %) wasadded. The reaction mixture was stirred at room temperature for 18 h.Solvent was removed under reduced pressure, and the residue obtained waspurified by HPLC on a reverse phase column (Altech Altima C-18, 10×299mm, A=water, B=acetonitrile, 10 to 60% B in 50 min, flow 2 mL/min) toyield the title compound (0.015 g, 41%) as a white solid.

¹H NMR (CD₃OD): δ 0.85 (s, 3H, Me), 3.61 (m, 1H), 3.82 (m, 1H) 3.99-4.86(m, 2H), 6.26 (s, 1H), 8.10 (s, 2H) 8.22(s, 1H); ¹³C NMR (CD₃OD): 20.13,61.37, 73.79, 80.42, 84.01, 93.00, 102.66, 112.07, 130.07, 151.40,152.74, 159.12, 169.30. HRMS (FAB) Calcd for C₁₃H₁₇N₄O₆+325.1148, found325.1143.

EXAMPLE 1374-Amino-7-(2-C-vinyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine

Step A:3,5-Bis-O-(2,4-dichlorophenylmethyl)-2-C-vinyl-1-O-methyl-α-D-ribofuranose

Cerium chloride heptahydrate (50 g, 134.2 mmol) was finely crushed in apre-heated mortar and transferred to a round-bottom flask equipped witha mechanical stirrer. The flask was heated under high vacuum overnightat 160° C. The vacuum was released under argon and the flask was cooledto room temperature. Anhydrous THF (300 mL) was cannulated into theflask. The resulting suspension was stirred at room temperature for 4 hand then cooled to −78° C. Vinylmagnesium bromide (1M in THF, 120 mL,120 mmol) was added and stirring continued at −78° C. for 2 h. To thissuspension was added a solution of3,5-bis-O-(2,4-dichlorophenylmethyl)-1-O-methyl-α-D-erythro-pentofuranose-2-ulose(14 g, 30 mmol) [from Example 2, Step B] in anhydrous THF (100 mL),dropwise with constant stirring. The reaction was stirred at −78° C. for4 h. The reaction was quenched with saturated ammonium chloride solutionand allowed to come to room temperature. The mixture was filteredthrough a celite pad and the residue washed with Et₂O (2×500 mL). Theorganic layer was separated and the aqueous layer extracted with Et₂O(2×200 mL). The combined organic layers were dried over anhydrous Na₂SO₄and concentrated to a viscous yellow oil. The oil was purified by flashchromatography (SiO₂, 10% EtOAc in hexanes). The title compound (6.7 g,13.2 mmol) was obtained as a pale yellow oil.

Step B:4-Chloro-7-[3,5-bis-O-(2,4-dichlorophenylmethyl)-2-C-vinyl-β-D-ribofuranosyl]-7H-pyrrolo[2,3-d]pyrimidine

To a solution of the compound from Step A (6.4 g, 12.6 mmol) inanhydrous dichloromethane (150 mL) at −20° C. was added HBr (30%solution in AcOH, 20 mL, 75.6 mmol) dropwise. The resulting solution wasstirred between −10° C. and 0° C. for 4 h, evaporated in vacuo andco-evaporated with anhydrous toluene (3×40 mL). The oily residue wasdissolved in anhydrous acetonitrile (100 mL) and added to a solution ofthe sodium salt of 4-chloro-1H-pyrrolo[2,3-d]pyrimidine (5.8 g, 37.8mmol) in acetonitrile (generated in situ as described in Example 62) at−20° C. The resulting mixture was allowed to come to room temperatureand stirred at room temperature for 24 h. The mixture was thenevaporated to dryness, taken up in water and extracted with EtOAc (2×300mL). The combined extracts were dried over Na₂SO₄, filtered andevaporated. The crude mixture was purified by flash chromatography(SiO₂, 10% EtOAc in hexanes) and the title compound (1.75 g) isolated asa white foam.

Step, C:4-Amino-7-[3,5-bis-O-(2,4-dichlorophenylmethyl)-2-C-vinyl-β-D-ribofuranosyl]-7H-pyrrolo[2,3-d]pyrimidine

The compound from Step B (80, mg) was dissolved in the minimum amount of1,4-dioxane and placed in a stainless steel bomb. The bomb was cooled to−78° C. and liquid ammonia was added. The bomb was sealed and heated at90° C. for 24 h. The ammonia was allowed to evaporate and the residueconcentrated to a white solid which was used in the next step withoutfurther purification.

Step D:4-Amino-7-(2-C-vinyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyridine

To a solution of the compound from Step C (60 mg) in dichloromethane at−78° C. was added boron trichloride (1M in dichloromethane) dropwise.The mixture was stirred at −78° C. for 2.5 h, then at −30° C. to −20° C.for 3 h. The reaction was quenched by addition ofmethanol/dichloromethane (1:1) and the resulting mixture stirred at −15°C. for 0.5 h, then neutralized with aqueous ammonia at 0° C. and stirredat room temperature for 15 min. The solid was filtered and washed withmethanol/dichloromethane (1:1). The combined filtrate was evaporated andthe residue purified by flash chromatography (SiO₂, 10% methanol inEtOAc containing 0.1% triethylamine). The fractions containing theproduct were evaporated to give the title compound as a white solid (10mg).

¹H NMR (DMSO-d6): δ 3.6 (m, 1H, H-5′), 3.8 (m, 1H, H-5″), 3.9 (m d, 1-H,H4′), 4.3 (t, 1H, H-3′), 4.8-5.3(m, 6H, CH═CH₂, 2′-OH, 3′-OH, 5′-OH)6.12 (s, 1H, H-1′), 6.59 (d, 1H, H-5), 7.1 (br s, 1H, NH2), 7.43 (d, 1H,H-6), 8.01 (s, 1H, H-2).

ES-MS: Found: 291.1 (M−H⁻); calc. for C₁₃H₁₆N₄O₄−H⁻: 291.2.

EXAMPLE 1384-Amino-7-(2-C-hydroxymethyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine

Step A:4-Chloro-7-[3,5-bis-O-(2,4-dichlorophenylmethyl)-2-C-hydroxymethyl-β-D-ribofuranosyl]-7H-pyrrolo[2,3-d]pyrimidine

To a solution of the compound from Example 137, Step B (300 mg, 0.48mmol) in 1,4-dioxane (5 mL) were added N-methylmorpholine-N-oxide (300mg, 2.56 mmol) and osmium tetroxide (4% solution in water, 0.3 mL). Themixture was stirred in the dark for 14 h. The precipitate was removed byfiltration through a celite plug, diluted with water (3×), and extractedwith EtOAc. The EtOAc layer was dried over Na₂SO₄ and concentrated invacuo. The oily residue was taken up in dichloromethane (5 mL) andstirred over NaIO₄ on silica gel (3 g, 10% NaIO₄) for 12 h. The silicagel was removed by filtration and the residue was evaporated and takenup in absolute ethanol (5 mL). The solution was cooled in an ice bathand sodium borohydride (300 mg, 8 mmol) was added in small portions. Theresulting mixture was stirred at room temperature for 4 h and thendiluted with EtOAc. The organic layer was washed with water (2×20 mL),brine (20 mL) and dried over Na₂SO₄. The solvent was evaporated and theresidue purified by flash chromatography (SiO₂, 2:1 hexanes/EtOAc) togive the title compound (160 mg, 0.25 mmol) as white flakes.

Step B:4-Amino-7-[3,5-bis-O-(2,4-dichlorophenylmethyl)-2-C-hydroxymethyl-β-D-ribofuranosyl]-7H-pyrrolo[2,3-d]pyrimidine

The compound from Step A (150 mg, 0.23 mmol) was dissolved in theminimum amount of 1,4-dioxane (10 mL) and placed in a stainless steelbomb. The bomb was cooled to −78° C. and liquid ammonia was added. Thebomb was sealed and heated at 90° C. for 24 h. The ammonia was allowedto evaporate and the residue concentrated to a white solid which wasused in the next step without further purification.

Step C:4-Amino-7-(2-C-hydroxymethyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine

The compound from Step B (120 mg, 0.2 mmol) was dissolved in 1:1methanol/dichloromethane, 10% Pd-C was added, and the suspension stirredunder an H₂ atmosphere for 12 h. The catalyst was removed by filtrationthrough a celite pad and washed with copious amounts of methanol. Thecombined filtrate was evaporated in vacuo and the residue was purifiedby flash chromatography (SiO₂, 10% methanol in EtOAc containing 0.1%triethylamine) to give the title compound (50 mg) as a white powder.

¹H NMR (CD₃OD): δ 3.12 (d, 1H, CH₂′), 3.33 (d, 1H, CH₂″), 3.82 (m, 1H,H-5′), 3.99-4.1(m, 2H, H-4′, H-5″), 4.3 (d, 1H, H-3′), 6.2 (s, 1H,H-1′), 6.58 (d, 1H, H-5), 7.45 (d, 1H, H-6), 8.05 (s, 1H, H-2).

LC-MS: Found: 297.2 (M+H⁺); calc. for C₁₂H₁₆N₄O₅+H⁺: 297.3.

EXAMPLE 1394-Amino-7-(2-C-fluoromethyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine

Step A:4-Chloro-7-[3,5-bis-O-(2,4-dichlorophenylmethyl)-2-C-fluoromethyl-β-D-ribofuranosyl]-7H-pyrrolo[2,3-d]pyrimidine

To a solution of the compound from Example 138, Step A (63 mg, 0.1 mmol)in anhydrous dichloromethane (5 mL) under argon, were added4-dimethylaminopyridine (DMAP) (2 mg, 0.015 mmol) and triethylamine (62μL, 0.45 mmol). The solution was cooled in an ice bath andp-toluenesulfonyl chloride (30 mg, 0.15 mmol) was added. The reactionwas stirred at room temperature overnight, washed with NaHCO₃ (2×10 mL),water (10 mL), brine (10 mL), dried over Na₂SO₄ and concentrated to apink solid in vacuo. The solid was dissolved in anhydrous THF (5 mL) andcooled in an icebath. Tetrabutylammonium fluoride (1M solution in THF, 1mL, 1 mmol) was added and the mixture stirred at room temperature for 4h. The solvent was removed in vacuo, the residue taken up indichloromethane, and washed with NaHCO₃ (2×10 mL), water (10 mL) andbrine (10 mL). The dichloromethane layer was dried over anhydrousNa₂SO₄, concentrated in vacuo, and purified by flash chromatography(SiO₂, 2:1 hexanes/EtOAc) to afford the title compound (20 mg) as awhite solid.

Step B:4-Amino-7-[3.5-bis-O-(2,4-dichlorophenylmethyl)-2-C-fluoromethyl-β-D-ribofuranosyl]-7H-pyrrolo[2,3-d]pyrimidine

The compound from Step A (18 mg, 0.03 mmol) was dissolved in the minimumamount of 1,4-dioxane and placed in a stainless steel bomb. The bomb wascooled to −78° C. and liquid ammonia was added. The bomb was sealed andheated at 90° C. for 24 h. The ammonia was allowed to evaporate and theresidue concentrated to a white solid which was used in the next stepwithout further purification.

Step C:4-Amino-7-(2-C-fluoromethyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine

The compound from Step B (16 mg) was dissolved in 1:1methanol/dichloromethane, 10% Pd—C was added, and the suspension stirredunder an H₂ atmosphere for 12 h. The catalyst was removed by filtrationthrough a celite pad and washed with copious amounts of methanol. Thecombined filtrate was evaporated in vacuo and the residue was purifiedby flash chromatography (SiO₂, 10% methanol in EtOAc containing 0.1%triethylamine) to give the title compound (8 mg) as a white powder.

¹H NMR (DMSO-d₆): δ 3.6-3.7 (m, 1H, 1H-5′), 3.8-4.3 (m, 5H, H-5″, H-4′,H-3′, CH₂) 5.12 (t, 1H, 5′-OH), 5.35 (d, 1H, 3′-OH), 5.48 (s, 1H,2′-OH), 6.21 (s, 1H, H-1′), 6.52 (d, 1H, H-5), 6.98 (br s, 2H, NH2),7.44 (d, 1 H, H-6), 8.02 (s, 1H, H-2). ¹⁹F NMR (DMSO-d₆): δ −230.2 (t).

ES-MS: Found: 299.1 (M+H⁺), calc.for C₁₂H₁₅FN₄O₄+H⁺: 299.27.

EXAMPLES 140 AND 1414-Amino-7-(3-deoxy-2-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidineand4-amino-7-(3-deoxy-2-C-methyl-β-D-arabinofuranosyl)-7H-pyrrolo[2,3-d]-pyrimidine

Step A:7-[2,5-Bis-O-(tert-butyldimethylsilyl)-β-D-ribofuranosyl]-7H-pyrrolo[2,3-d]pyrimidineand7-[3,5-Bis-O-(tert-butyldimethylsilyl)-β-D-ribofuranosyl]-7H-pyrrolo[2,3-d]pyrimidine

To a stirred solution of tubercidin (5.0 g, 18.7 mmol) in a mixture ofpyridine (7.5 mL) and DMF(18.5mL) was added silver nitrate (6.36 g, 38.8mmol). This mixture was stirred at room temperature for 2 h. It wascooled in an ice bath and THF (37.4 mL) and tert-butyldimethylsilylchloride (5.6 g, 37 mmol) was added and the mixture was stirred at roomtemperature for 2 h. The mixture was then filtered through a pad ofcelite and washed with THF. The filtrate and washings were diluted withether containing a small amount of chloroform. The organic layer waswashed successively with sodium bicarbonate and water (3×50 mL), driedover anhydrous sodium sulfate and concentrated. The pyridine was removedby coevaporation with toluene and the residue was purified by flashchromatography on silica gel using 5-7% MeOH in CH₂Cl₂ as the eluent;yield 3.0 g.

Step B:7-[2,5-Bis-O-(tert-butyldimethylsilyl)-β-D-ribofuranosyl)]-4-[di-(4-methoxyphenyl)phenylmethyl]amino-7H-pyrrolo[2.3-d]pyrimidineand7-[3,5-bis-O-(tert-butyldimethylsilyl)-β-D-ribofuranosyl]-4-[di-(4-methoxyphenyl)phenylmethyl]amino-7H-pyrrolo[2,3-d]pyrimidine

To a solution of mixture of the compounds from Step A (3.0 g, 6.0 mmol)in anhydrous pyridine (30 mL) was added 4,4′-dimethoxytrityl chloride(2.8 g, 8.2 mmol) and the reaction mixture was stirred at roomtemperature overnight. The mixture was then triturated with aqueouspyridine and extracted with ether. The organic layer was washed withwater, dried over anhydrous sodium sulfate and concentrated to a yellowfoam (5.6 g). The residue was purified by flash chromatography oversilica gel using 20-25% EtOAc in hexanes as the eluent. The appropriatefractions were collected and concentrated to furnish2′,5′-O-bis-O-(tert-butyldimethylsilyl)- and3′,5′-bis-O-(tert-butyldimethylsilyl) protected nucleosides as colorlessfoams (2.2 g and 1.0 g, respectively).

Step C:7-[2,5-Bis-O-(tert-butyldimethylsilyl)-3-O-tosyl-β-D-ribofuranosyl)]-4-[di-(4methoxyphenyl)phenylmethyl]amino-7H-pyrrolo[2,3-d]pyrimidine

To an ice-cooled solution of2′,5′-bis-O-(tert-butyldimethylsilyl)-protected nucleoside from Step B(2.0 g, 2.5 mmol) in pyridine (22 mL) was added p-toluenesulfonylchloride (1.9 g, 9.8 mmol). The reaction mixture was stirred at roomtemperature for four days. It was then triturated with aqueous pyridine(50%, 10 mL) and extracted with ether (3×50 mL) containing a smallamount of CH₂Cl₂ (10 mL). The organic layer was washed with sodiumbicarbonate and water (3×30 mL). The organic layer was dried overanhydrous Na₂SO₄ and concentrated. Pyridine was removed byco-evaporation with toluene (3×25 mL). The residual oil was filteredthrough a pad of silica gel using hexane:ethyl acetate (70:30) aseluent; yield 1.4 g.

Step D:4-[di-(4-methoxyphenyl)phenylmethyl]amino-7-[3-O-tosyl-β-D-ribofuranosyl-7H-pyrrolo[2,3-d]pyrimidine

A solution of the compound from Step C (1.0 g, 1.1 mmol) and THF (10 mL)was stirred with tetrabutylammonium fluoride (1M solution in THF, 2.5mL) for 0.5 h. The mixture was cooled and diluted with ether (50 mL).The solution was washed with water (3×50 mL), dried over anhydrousNa₂SO₄, and concentrated to an oil. The residue was purified by passingthrough a pad of silica gel using hexane: ethyl acetate (1:1) as eluent;yield 780 mg.

Step E:4-Amino-7-(3-deoxy-2-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]-pyrimidineand4-amino-7-(3-deoxy-2-C-methyl-β-D-arabinofuranosyl)-7H-pyrrolo-[2,3-d]pyrimidine

A solution of CH₃MgI (3.0 M solution in ether, 3.0 mL) in anhydroustoluene (3.75 mL) was cooled in an ice bath. To this was added asolution of the compound from Step D (500 mg, 0.8 mmol) in anhydroustoluene (3.7 mL). The resulting mixture was stirred at room temperaturefor 3.5 h. It was cooled and treated with aqueous NH₄Cl solution andextracted with ether (50 mL containing 10 mL of CH₂Cl₂). The organiclayer was separated and washed with brine (2×30 mL) and water (2×25 mL),dried over anhydrous Na₂SO₄ and concentrated to an oil which waspurified by flash chromatography on silica gel using 4% MeOH in CH₂Cl₂to furnish the 2-C-α-methyl compound (149 mg) and the 2-C-β-methylcompound (34 mg). These derivatives were separately treated with 80%acetic acid and the reaction mixture stirred at room temperature for 2.5h. The acetic acid was removed by repeated co-evaporation with ethanoland toluene. The residue was partitioned between chloroform and water.The aqueous layer was washed with chloroform and concentrated. Theevaporated residue was purified on silica gel using 5-10% MeOH in CH₂Cl₂as the eluent to furnish the desired compounds as white solids.

4-Amino-7-(3-deoxy-2-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine(9.0 mg)

¹H NMR (DMSO-d₆): δ 0.74 (s, 3H, CH₃), 1.77 (dd, 1H, H-3′), 2.08 (t, 1H,H-3″), 3.59 (m, 1H, H-5′), 3.73 (m, 1H, H-5″), 4.15 (m, 1H, H-4′), 5.02(t, 1H, OH-5′), 5.33 (s, 1H, OH-2′), 6.00 (s, 1H, H-1′), 6.54 (d, 1H,H-7), 6.95 (br s, 2H, NH₂), 7.47 (d, 1H, H-8), 8.00 (s, 1H, H-2); ES-MS:263.1 [M−H].

4-Amino-7-(3-deoxy-2-C-methyl-β-D-arabinofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine(15 mg):

¹H NMR (DMSO-d₆): δ 1.23 (s, 3H, CH₃), 2.08 (ddd, 2H, H-3 and 3″), 3.57(m, 2H, H-5′ and 5″), 4.06 (m, 1H, H4), 5.10 (s, 1H, OH-2′), 5.24 (t,1H, OH-5′), 6.01 (s, 1H, H-1′), 6.49 (d, 1H, H-7), 6.89 (br s, 2H, NH₂),7.35 (d, 1H, H-8), 8.01 (s,1H,H-2).

ES-MS: 265.2[M+H].

EXAMPLE 1424-Amino-7-(2,4-C-dimethyl-β-D-ribofiuranosyl)-7H-pyrrolo[2,3-d]pyrimidine

Step A: 5-Deoxy-1,2-O-isopropylidene-D-xylofuranose

1,2-O-Isopropylidene-D-xylofuranose (38.4 g, 0.2 mol),4-dimethylaminopyridine (5 g), triethylamine (55.7 mL, 0.4 mol) weredissolved in dichloromethane (300 mL). p-Toluenesulfonyl chloride (38.13g, 0.2 mol) was added and the reaction mixture was stirred at roomtemperature for 2 h. The reaction mixture was then poured into saturatedaqueous sodium bicarbonate (500 mL) and the two layers were separated.The organic layer was washed with aqueous citric acid solution (20%, 200mL), dried (Na₂SO₄) and evaporated to give a solid (70.0 g). The solidwas dissolved in dry THF (300 mL) and LiAlH₄ (16.0 g, 0.42 mol) wasadded in portions over 30 min. The mixture was stirred at roomtemperature for 15 h. Ethyl acetate (100 mL) was added dropwise over 30min and the mixture was filtered through a silica gel bed. The filtratewas concentrated and the resulting oil was chromatographed on silica gel(EtOAc/hexane 1/4) to afford the product as a solid (32.5 g).

Step B:3,5-Bis-O-(2,4-dichlorophenylmethyl)-1-O-methyl-4-methyl-α-D-ribofuranose

Chromium oxide (50 g, 0.5 mol), acetic anhydride (50 mL, 0.53 mol) andpyridine (100 mL, 1.24 mol) were added to dichloromethane (1 L) in anice water bath and the mixture was stirred for 15 min.5-Deoxy-1,2-O-isopropylidene-D-xylofuranose (32 g, 0.18 mol) indichloromethane (200 mL) was added, and the mixture was stirred at thesame temperature for 30 min. The reaction solution was diluted withethyl acetate (1 L) and filtered through a silica gel bed. The filtratewas concentrated to give a yellow oil. The oil was dissolved in1,4-dioxane (1 L) and formaldehyde (37%, 200 mL). The solution wascooled to 0° C. and solid KOH (50 g) was added. The mixture was stirredat room temperature overnight and was then extracted with ethyl acetate(6×200 mL). After concentration, the residue was chromatographed onsilica gel (EtOAc) to afford the product as an oil (1.5 g). The oil wasdissolved in 1-methyl-2-pyrrolidinone (20 mL) and2,4-dichlorophenylmethyl chloride (4 g, 20.5 mmol) and NaH (60%, 0.8 g)were added. The mixture was stirred overnight and diluted with toluene(100 mL). The mixture was then washed with saturated aqueous sodiumbicarbonate (3×50 mL), dried (Na₂SO₄) and evaporated. The residue wasdissolved in methanol (50 mL) and HCl in dioxane (4 M, 2 mL) was added.The solution was stirred overnight and evaporated. The residue waschromatographed on silica gel (EtOAc/hexane:1/4) to afford the desiredproduct as an oil (2.01 g).

Step C:3,5-Bis-O-(2,4-dichlorophenylmethyl)-2,4-di-C-methyl-1-O-methyl-α-D-ribofuranose

The product (2.0 g, 4.0 mmol) from Step B and Dess-Martin periodinane(2.0 g) in dichloromethane (30 mL) were stirred overnight at roomtemperature and was then concentrated under reduced pressure. Theresidue was triturated with ether ether (50 mL) and filtered. Thefiltrate was washed with a solution of Na₂S₂O₃.5H₂O(2.5 g) in saturatedaqueous sodium bicarbonate solution (50 mL), dried (MgSO₄), filtered andevaporated. The residue was dissolved in anhydrous Et₂O (20 mL) and wasadded dropwise to a solution of MeMgBr in Et₂O (3 M, 10 mL) at −78° C.The reaction mixture was allowed to warm to −30° C. and stirred at −30°C. to −15° C. for 5 h, then poured into saturated aqueous ammoniumchloride (50 mL). The two layers were separated and the organic layerwas dried (MgSO₄), filtered and concentrated. The residue waschromatographed on silica gel (EtOAc/hexane: 1/9) to afford the titlecompound as a syrup (1.40 g).

Step D:4-Chloro-7-[3,5-bis-O-(2,4-dichlorophenylmethyl)-2,4-di-C-methyl-β-D-ribofuranosyl]-7H-pyrrolo[2,3-d]pyrimidine

To the compound from Step C (0.70 g, 1.3 mmol) was added HBr (5.7 M inacetic acid, 2 mL). The resulting solution was stirred at roomtemperature for 1 h, evaporated in vacuo and co-evaporated withanhydrous toluene (3×10 mL). 4-Chloro-1H-pyrrolo[2,3-d]pyrimidine (0.5g, 3.3 mmol) and powdered KOH (85%, 150 mg, 2.3 mmol) were stirred in1-methyl-2-pyrrolidinone (5 mL) for 30 min and the mixture wasco-evaporated with toluene (10 mL). The resulting solution was pouredinto the above bromo sugar residue and the mixture was stirredovernight. The mixture was diluted with toluene (50 mL), washed withwater (3×50 mL) and concentrated under reduced pressure. The residue waschromatographed on silica gel eluting with (EtOAc/Hexane 15/85) toafford a solid (270 mg).

Step E:4-Amino-7-(2,4-di-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine

The compound from Step D (270 mg) was dissolved in dioxane (2 mL) andliquid ammonia (20 g) was added in a stainless steel autoclave. Themixture was heated at 100° C. for 15 h, then cooled and evaporated. Theresidue was chromatographed on silica gel (EtOAc) to afford a solid (200mg). The solid (150 mg) and Pd/C (10% 150 mg) in methanol (20 mL) wereshaken under H₂ (30 psi) for 3 h, filtered and evaporated. The residuewas chromatographed on silica gel (MeOH/CH₂Cl₂: 1/9) to afford thedesired product as a solid (35 mg).

¹H NMR (DMSO-d₆): δ 0.65 (s, 3H), 1.18 (s, 3H), 3.43 (m, 2H), 4.06 (d,1H, J 6.3 Hz), 4.87 (s, 1H), 5.26 (br, 1H), 5.08 (d, 1H, J 6.3 Hz), 5.25(t, 1H, J 3.0 Hz), 6.17 (s, 1H), 6.54 (d, 1H, J 3.5 Hz), 6.97 (s, br,2H), 7.54 (d, 1H, J 3.4 Hz), 8.02 (s, 1H).

¹³C NMR (DMSO-d₆): δ 18.19, 21.32, 65.38, 73.00, 79.33, 84.80, 90.66,99.09, 102.41, 121.90, 149.58, 151.48, 157.38.

LC-MS: Found: 295.1 (M+H⁺); calculated for C₁₃H₁₈N₄O₄+H⁺: 295.1

EXAMPLE 1434-Amino-7-(3-deoxy-3-fluoro-2-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine

Step A: 3-Deoxy-3-fluoro-1-O-methyl-5-O-toluoyl-α-D-ribofuranose

1,2-O-Isopropylidene-D-xylofuranose (9.0 g, 50 mmol) and p-toluoylchloride (7.0 mL, 50 mmol) in pyridine (50 mL) were stirred for 30 min.Water (10 mL) was added and the mixture was concentrated under reducedpressure. The residue was dissolved in toluene (500 mL) and the solutionwas washed with water (200 mL) and saturated aqueous sodium bicarbonate(200 mL). The two layers were separated and the organic layer wasevaporated. The residue was dissolved in methanol (100 mL) and HCl indioxane (4 M, 10 mL) was added. The mixture was stirred at roomtemperature overnight and was then evaporated under reduced pressure.The resulting oil was chromatographed on silica gel (EtOAc/hexane: 1/1)to afford an oil (10.1 g). The oil was dissolved in dichloromethane (100mL) and diethylaminosulfur trifluoride (DAST) (5.7 mL) was added. Themixture was stirred overnight and was then poured into saturated aqueoussodium bicarbonate solution (100 mL). The mixture was extracted withtoluene (2×50 mL) and the combined organic layers were concentrated. Theresidue was chromatographed on silica gel (EtOAc/hexane: 15/85) toafford the title compound as an oil (1.50 g).

Step B:3-Deoxy-3-fluoro-2-C-methyl-1-O-methyl-5-O-toluoyl-α-D-ribofuranose

The product from Step A (1.0 g, 3.5 mmol) and Dess-Martin periodinane(2.5 g) in dichloromethane (20 mL) were stirred overnight at roomtemperature and was then concentrated under reduced pressure. Theresidue was triturated with diethyl ether (50 mL) and filtered. Thefiltrate was washed with a solution of Na₂S₂O₃.5H₂O (12.5 g) insaturated aqueous sodium bicarbonate (100 mL), dried (MgSO₄), filteredand evaporated. The residue was dissolved in anhydrous THF (50 mL).TiCl₄ (3 mL) and methyl magnesium bromide in ethyl ether (3 M, 10 mL)were added at −78° C. and the mixture was stirred at −50 to −30° C. for2 h. The mixture was poured into saturated aqueous sodium bicarbonatesolution (100 mL) and filtered through Celite. The filtrate wasextracted with toluene (100 mL) and evaporated. The residue waschromatographed on silica gel (EtOAc/hexane: 15/85) to afford the titlecompound as an oil (150 mg).

Step C:4-Amino-7-(3-deoxy-3-fluoro-2-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyriridine

The product from Step B (150 mg, 0.5 mmol) was dissolved in HBr (30%) inacetic acid (2 mL). After one hour, the mixture was evaporated underreduced pressure and co-evaporated with toluene (10 mL).4-Chloro-1H-pyrrolo[2,3-d]pyrimidine (0.5 g, 3.3 mmol) and powdered KOH(85%, 150 mg, 2.3 mmol) were stirred in DMF (3 mL) for 30 min and themixture was co-evaporated with toluene (2 mL). The resulting solutionwas poured into the above bromo sugar and the mixture was stirredovernight. The mixture was diluted with toluene (50 mL), washed withwater (3×50 mL) and concentrated under reduced pressure. The residue waschromatographed on silica gel (EtOAc/hexane 15/85) to afford an oil (60mg). The oil was dissolved in dioxane (2 mL) and liquid ammonia (20 g)was added in a stainless steel autoclave. The mixture was heated at 85°C. for 18 h, then cooled and evaporated. The residue was chromatographedon silica gel (methanol/dichloromethane: 1/9) to afford the titlecompound as a solid (29 mg).

¹H NMR (DMSO-d₆): δ 0.81 (s, 3H), 3.75 (m, 2H), 4.16 (m, 1H), 5.09 (dd,1H, J 53.2, 7.8 Hz), 5.26 (br, 1H), 5.77 (s, 1H), 6.15 (d, 1H, J 2.9Hz), 6.59 (d, 1H, J 3.4 Hz), 7.02 (s br, 2H), 7.39 (d, 1H, J 3.4 Hz),8.06 (s, 1H).

¹³C NMR (DMSO-d₆): 19.40, 59.56, 77.24, 79.29, 90.15, 91.92, 99.88,102.39, 121.17, 149.80, 151.77, 157.47.

¹⁹F NMR (DMSO-d₆): δ 14.66 (m).

ES-MS: Found: 283.1 (M+H⁺); calculated for C₁₂H₁₅FN₄O₃+H⁺: 283.1.

EXAMPLE 144 8-Amino-2′-C-methyladenosine

Step A: 8-Bromo-2′-C-methyladenosine

To a solution of 2′-C-methyladenosine [for preparation, see J. Med.Chem. 41: 1708 (1998)] (138 mg, 0.5 mmol) in DMF (4 mL) was addedN-bromosuccinimide (231 mg, 1.35 mmol). The solution was stirredprotected from light at rt for 2 d and then evaporated in vacuo. Thecrude product was purified on a silica gel column (3×9 cm) usingdichloromethane/methanol (25/1, 20/1 and 15/1) as eluent. Fractionscontaining the product were pooled and evaporated in vacuo to give thedesired product (38 mg) as a white solid.

Step B: 8-Amino-2′-C-methyladenosine

A solution of the compound from Step A (38 mg, 0.11 mmol) in liquidammonia (10 mL) was heated in a stainless steel autoclave at 105° C. for1 d, then cooled and evaporated. The residue was purified by HPLC [C-18Phenomenex Luna (10μ; 250×21.2 mm) RP-column; solvents: (A) water, (13)acetonitrile; Linear gradient: 2-35% B in 76 min.] to yield the titlecompound (12 mg) as a white fluffy material after freeze-drying.

¹H NMR (DMSO-d₆): δ 0.70 (s, 3H, Me), 3.55-3.75 (m, 3H, H-5′, H-5″,H-4′), 4.03 (m, 1H, H-3′), 4.81 (s, 1H, 2′-OH), 5.10 (d, 1H, 3′-OH),5.45 (t, 1H, 5′-OH), 5.86 (s, 1H, H-1′), 6.30, 6.39 (2s, 6H, 2 NH₂),7.78 (s, 1H, H-2).

ES-MS: Found: 295.0 (M−H⁺).

EXAMPLE 1454-Amino-7-(2-C,2-O-dimethyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine

Step A:4-chloro-7-[3,5-bis-O-(2,4-dichlorophenylmethyl)-2-C,2-O-dimethyl-β-D-ribofuranosyl]-7H-pyrrolo[2,3-d]pyrimidine

To a pre-cooled (0° C.) solution of the compound from Example 62, Step D(618 mg, 1.0 mmol) in THF (8 mL) was added methyl iodide (709 mg, 5.0mmol) and NaH (60% in mineral oil) (44 mg, 1.1 mmol). The resultingmixture was stirred overnight at rt and then poured into a stirredmixture of saturated aqueous ammonium chloride (50 mL) anddichloromethane (50 mL). The organic layer was washed with water (50mL), dried (MgSO₄) and evaporated in vacuo. The resulting crude productwas purified on silica gel using ethyl acetate/hexane as the eluent.Fractions containing the product were pooled and evaporated in vacuo togive the desired product (735 mg) as a colorless foam.

Step B:4-amino-7-[3,5-bis-O-(2,4-dichlorophenylmethyl)-2-C,2-O-dimethyl-β-D-ribofuranosyl]-7H-pyrrolo[2,3-d]pyrimidine

To the compound from Step A (735 mg, 1.16 mmol) was added methanolicammonia (saturated at 0° C.) (20 mL). The mixture was heated in astainless steel autoclave at 80° C. overnight, then cooled and thecontent evaporated in vacuo. The crude mixture was purified on silicagel using ethyl acetate/hexane as the eluent. Fractions containing theproduct were pooled and evaporated in vacuo to give the desired product(504 mg) as colorless foam.

Step C:4-amino-7-(2-C,2-O-dimethyl-β-D-ribofiuranosyl)-7H-pyrrolo[2,3-d]pyrimidine

A mixture of the product from Step C (64 mg, 0.1 mmol), MeOH (5 mL),Et₃N (0.2 mL) and 10% Pd/C (61 mg) was hydrogenated on a Parrhydrogenator at 50 psi at room temperature overnight. The mixture wasfiltered throught celite, evaporated in vacuo and filtered through a padof silica gel using 2% methanol in dichloromethane as eluent. Thedesired product was collected and evaporated in vacuo. The compound wasredissolved in methanol (10 mL) and 10% Pd/C (61 mg) was added. Themixture was hydrogenated on a Parr hydrogenator at 55 psi at roomtemperature for two weeks. The mixture was filtered through celite,evaporated in vacuo and purified on silica gel using 10% methanol indichloromethane as eluent. Fractions containing the product were pooledand evaporated in vacuo to give the desired product (110 mg) as acolorless foam.

¹H NMR (DMSO-d₆): δ 0.68 (s, 3H,), 3.40 (s, 3H), 3.52-3.99 (overlappingm, 4H), 4.92 (d, 1H), 5.07 (t, 1H), 6.26 (s, 1H), 6.55 (d, 1H), 7.00sbr, 2H), 7.46 (d, 1H), 8.05 (s, 1H).

LC-MS: Found: 293.1 (M−H⁺); calc. for C₁₂H₁₆N₄O₄−H⁺: 293.12.

EXAMPLE 1464-Methylamino-7-(2-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine

The compound from Step E of Example 62 (200 mg, 0.67 mmol) was added tomethylamine (5 mL condensed in a small stainless steel autoclave) andwarmed at 85° C. for 48 h, then cooled and evaporated in vacuo. Thecrude mixture was purified on a silica gel with ethanol as the eluent togive the title compound which separated as an amorphous solid aftertreatment with MeCN. The amorphous solid was dissolved in water andlyophilized to give a colorless powder (144 mg).

¹H NMR (DMSO-d₆): δ 0.63 (s, 3H, CH₃), 3.32 (s, 3H, N CH₃), 3.58-3.67(m, 1H, H-5′), 3.79-3.39 (m, 3H, H-5″, H4′, H-3′), 5.03 (s, 1H, 2′-OH),5.04-5.11 (1H,3′-OH, 1H, 5′-OH), 6.14 (s, 1H, H-1′), 6.58 (d, 1H,J_(5,6)=3.6 Hz, H-5), 7.46 (d, 1H, H-6), 7.70 (br s, 1H, NH), 8.14 (s,1H, H-2).

LC-MS: Found: 295.1 (M−H⁺); calc. for C₁₃H₁₈N₄O₄+H⁺: 294.3.

EXAMPLE 1474-Dimethylamino-7-(2-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine

The compound from Step E of Example 62 (200 mg, 0.67 mmol) was added todimethylamine (5 mL condensed in a small stainless steel autoclave) andwarmed at 85° C. for 48 h, then cooled and evaporated in vacuo. Thecrude mixture was purified on a silica gel with ethanol as the eluent togive the title compound which separated as an amorphous solid aftertreatment with MeCN. The amorphous solid was dissolved in water andlyophilized to give a colorless powder (164 mg).

¹H NMR (DMSO-d₆): δ 0.64 (s, 3H, CH₃), 3.29 (s, 3H, N CH₃), 3.32 (s, 3H,N CH₃), 3.60-3.66 (m, 1H, H-5′), 3.77-3.97 (m, 3H, H-5″, H-4′, H-3′),5.04 (s, 1H, 2′-OH), 5.06-5.11 (1H, 3′-OH, 1H, 5′-OH), 6.21 (s, 1H,H-1′), 6.69 (d, 1H, J_(5,6)=3.6 Hz, H-5), 7.55 (d, 1H, H-6), 8.13 (s,1H, H-2).

LC-MS: Found: 309.3 (M−H⁺); calc. for C₁₄H₂₀N₄O₄+H⁺: 308.33.

EXAMPLE 1484-Cyclopropylamino-7-(2-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine

The compound from Step E of Example 62 (200 mg, 0.67 mmol) was added tocyclopropylamine (5 mL condensed in a small stainless steel autoclave)and warmed at 85° C. for 48 h, then cooled and evaporated in vacuo. Thecrude mixture was purified on a silica gel with ethanol as the eluent togive the title compound which separated as an amorphous solid aftertreatment with MeCN. The amorphous solid was dissolved in water andlyophilized to give a colorless powder (148 mg).

¹H NMR (DMSO-d₆): δ 0.51-0.58 (m, 2H), 0.64 (s, 3H, CH₃), 0.74-0.076 (m,2H), 3.62-3.67 (m, 1H, H-5′), 3.79-3.82 (m, 3H, H-5″), 3.92-3.96 (m,H-4′, H-3′), 5.03 (s, 1H, 2′-OH), 5.05-5.10 (1H, 3′-OH, 1H, 5′-OH), 6.15(s, 1H, H-1′), 7.48 (d, 1H, J_(5,6)=3.6 Hz, H-5), 7.59 (d, 1H, H-6),8.13 (s, 1H, H-2).

LC-MS: Found: 321.1 (M−H⁺); calc. for C₁₅H₂₀N₄O₄+H⁺: 320.3.

EXAMPLE 1494-Amino-7-(3-C-methyl-β-D-xylofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine

Step A:7-[2,5-Bis-O-(tert-butyldimethylsilyl)-β-D-ribofuranosyl)]-4-[(4-methoxyphenyl)diphenylmethyl]amino-7H-pyrrolo[2,3-d]pyrimidineand7-[3,5-bis-O-(tert-butyldimethylsilyl)-β-D-ribofuranosyl]-4-[(4-methoxyphenyl)diphenylmethyl]amino-7H-pyrrolo[2,3-d]pyrimidine

To a solution of mixture of the compounds from Step A of Examples 140and 141 (0.32 g, 0.65 mmol) in anhydrous pyridine (6 mL) was addedmonomethoxytrityl chloride (0.30 g, 0.98 mmol) and the reaction mixturewas stirred at room temperature overnight. The mixture was thenconcentrated and the residue was partitioned between CH₂Cl₂ (70 mL) andwater (20 mL). The organic layer was washed with water and brine, dried(Na₂SO₄) and concentrated. The residue was purified on silica gel columnusing 5-13% EtOAc in hexanes as the eluent. The appropriate fractionswere collected and concentrated to furnish2′,5′-bis-O-(tert-butyldimethylsilyl)- and3′,5′-bis-O-(tert-butyldimethylsilyl) protected nucleosides as colorlessfoams (343 mg and 84 mg, respectively).

Step B:7-[2,5-Bis-O-(tert-butyldimethylsilyl)-β-D-erythro-pentofuranos-3-ulosyl]-4-[(4-methoxyphenyl)diphenylmethyl]amino-7H-pyrrolo[2,3-d]pyrimidine

To a well-stirred suspension of chromium trioxide (91 mg, 0.91 mmol) inCH₂Cl₂ (4 mL) at 0° C. were added pyridine (147 μL, 1.82 mmol) and thenacetic anhydride (86 μL, 0.91 mmol). The mixture was stirred at roomtemperature for 0.5 h. Then the 2′,5′-bis-O-(tert-butyldimethylsilyl)protected nucleoside from step A (343 mg 0.45 mmol) in CH₂Cl₂ (2.5 mL)was added and the mixture stirred at room temperature 2 h. The mixturewas then poured into ice-cold EtOAc (10 mL) and filtered through a shortsilica gel column using EtOAc as the eluent. The filtrate was evaporatedand the residue purified on a silica gel column with hexanes andhexanes/EtOAc (7/1) as the eluent to give the title compound (180 mg).

Step C:7-[2,5-Bis-O-(tert-butyldimethylsilyl)-3-C-methyl-β-D-ribofuranosyl)-4-[(4-methoxyphenyl)diphenylmethyl]amino-7H-pyrrolo[2,3-d]pyrimidineand7-[2,5-Bis-O-(tert-butyldimethylsilyl)-3-C-methyl-β-D-xylofuranosyl)-4-[(4-methoxyphenyl)diphenylmethyl]amino-7H-pyrrolo[2,3-d]pyrimidine

To a mixture of MeMgBr (3.0 M solution in ether; 0.17 mL, 0.5 mmol) inanhydrous hexanes (1.5 mL) at room temperature was added dropwise asolution of the compound from Step B (78 mg, 0.1 mmol) in anhydroushexanes (0.5 mL). After 2 h stirring at room temperature, the reactionmixture was poured into ice-cold water (10 mL) and diluted with EtOAc(20 mL), then filtered through Celite which was then thoroughly washedwith EtOAc. The layers were separated and the organic layer was washedwith brine, dried (Na₂SO₄) and concentrated. The residue was purified ona silica gel column using 8 to 25% EtOAc in hexanes as eluent to givethe 3-C-methyl xylo- (60 mg) and the 3-C-methyl ribo-isomer (20 mg).

Step D:4-Amino-7-(3-C-methyl-β-D-xylofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine

To an ice-cold solution of 3-C-methyl-xylo isomer from Step C (60 mg,0.08 mmol) in THF (2 mL) was added TBAF (1 M in THF; 0.32 ml, 0.32mmol). The reaction mixture was stirred at room temperature for 5 h,then diluted with CH₂Cl₂ (50 mL), washed with water (3×15 mL), dried,andevaporated. The residue was dissolved in dioxane (0.3 mL) and 80% aceticacid (3 mL) was added. The reaction mixture was stirred at roomtemperature for 1 d and then evaporated. The residue was co-evaporatedwith dioxane, taken up in water (50 mL) and washed with CH₂Cl₂ (2×10mL). The aqueous layer was concentrated and then freeze-dried. Theresidue was purified on silica gel column with CH₂Cl₂/MeOH (20/1 and10/1) as the eluent to give the title compound as a white fluffycompound after freeze drying (10 mg).

¹H NMR (CD₃CN): δ 1.28 (s, 3H, CH₃), 3.56 (br s, 1H, OH), 3.78 (m, 3H,H-4′, H-5′, H-5″), 4.10 (br s, 1H, OH), 4.44 (d, 1H, J_(2′,1′)=3.9 Hz,H-2′), 5.58 (d, 1H, H-1′), 5.85 (br s, 2H, NH₂), 6.15 (br s, 1H, OH),6.48 (d, 1H, J_(5,6)=3.7 Hz, H-5), 7.23 (d, 1H, H-6), 8.11 (s, 1H, H-2).ES-MS: 281 [MH]⁺.

EXAMPLE 1504-Amino-7-(3-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine

The ribo-isomer (20 mg) from Step C of Example 149 was deprotected usingthe procedure described in Step D of Example 32 to yield the titlecompound (4 mg).

¹H NMR (CD₃CN): δ 1.43 (s, 3H, CH₃), 3.28 (br s, 1H, OH), 3.58 (m, 2H,H-5′, H-5″), 3.99 (m, 1H, H-4′), 4.10 (br s, 1H, OH), 4.62 (d, 1H,J_(2′1′)=8.1 Hz, H-2′), 5.69 (d, 1H, H-1′), 5.88 (br s, 3H, OH, NH₂),6.45 (br s, 1H, OH), 6.51 (d, 1H, J_(5,6)=3.7 Hz, H-5), 7.19 (d, 1H,H-6), 8.12 (s, 1H, H-2). ES-MS: 281 [MH]⁺.

EXAMPLE 1512,4-Diamino-7-(2-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine

A mixture of the product from Step B of Example 118 (24 mg) in aqueousammonia (30%, 10 mL) was heated in a stainless steel autoclave at 100°C. overnight, then cooled and evaporated. The residue was purified on asilica gel column with CH₂Cl₂/MeOH (10/1 and 5/1) as the eluent toafford the title compound (15 mg).

¹H NMR (DMSO-d₆): δ 0.68 (s, 3H, CH₃), 3.48-3.58 (m 1H, H-5′), 3.68-3.73(m, 2H, H-5″, H-4′), 3.84 (m, 1H, H-3′), 4.72 (s, 1H, 2′-OH), 4.97-5.03(m, 2H, 3′-OH, 5′-OH), 5.45 (br s, 2H, NH₂), 6.00 (s, 1H, H-1′), 6.28(d, 1H, J=3.7 Hz, H-5), 6.44 (br s, 2H, NH₂) 6.92 (d, 1H J=3.7 Hz, H-6).

ES MS: 294.1 (M−H⁺).

EXAMPLE 1524-Amino-2-fluoro-7-(2-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine

To a solution of HF/pyridine (70%, 2 mL) diluted with pyridine (1 mL) at−30° C. is added the compound of Example 151 (60 mg, 0.2 mmol) in 0.5 mLpyridine followed by tert-butyl nitrite (36 μL, 0.3 mmol). Stirring iscontinued for 5 min −25° C. Then the solution is poured into ice-water(5 mL), neutralized with 2 N aqueous NaOH, and evaporated to dryness.The residue is purified on a silica gel column with CH₂Cl₂/MeOH (20/1and 10/1) as the eluent to afford the title compound.

EXAMPLE 1534-Amino-5-fluoro-7-(2-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine

Step A:4-Acetylamino-7-(2,3,5-tri-O-acetyl-2-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine

To a solution of the compound from step F of Example 62 (280 mg, 1.00mmol) in pyridine is added acetic anhydride (613 mg, 6.0 mmol). Theresulting solution is stirred overnight at ambient temperatureevaporated in vacuo and the resulting crude mixture is purified onsilica gel using ethyl acetate/hexane as the eluent. Fractionscontaining the desired product are pooled and evaporated in vacuo togive the desired product.

Step B:4-Acetylamino-5-bromo-7-(2,3,5-tri-O-acetyl-2-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine

To a pre-cooled (0° C.) solution of the compound from Step A (460 mg,1.00 mmol) in DMF is added N-bromosuccinimide (178 mg, 1.0 mmol) in DMF.The resulting solution is stirred at 0° C. for 30 min then at roomtemperature for another 30 min. The reaction is quenched by addition ofmethanol and evaporated in vacuo. The resulting crude mixture ispurified on silica gel using ethyl acetate/hexane as the eluent.Fractions containing the desired product are pooled and evaporated invacuo to give the desired product.

Step C:4-Amino-5-fluoro-7-(2-C-methyl-β-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine

To a pre-cooled (−78° C.) solution of the compound from Step B (529 mg,1.00 mmol) in THF is added butyl lithium (2M in hexanes) (0.5 mL, 1.00mmol). The resulting solution is stirred at −78° C. for 30 min and thenquenched with N-fluorobenzensulfonimide (315 mg, 1.00 mmol) in THF. Theresulting solution is very slowly allowed to come to ambient temperatureand then poured into a stirred mixture of saturated aqueous ammoniumchloride and dichloromethane. The organic phase is evaporated in vacuoand treated with ammonium hydroxide at 55° C. in a closed containerovernight. The resulting crude mixture is purified on silica gel usingdichloromethane/methanol as the eluent. Fractions containing the desiredproduct are pooled and evaporated in vacuo to give the desired product.

EXAMPLE 1544-Amino-1-(2-C-methyl-β-D-ribofuranosyl)-1H-pyrazolo[3,4-d]pyrimidine

Step A:4-Amino-1-[3,5-bis-O-(2,4-dichlorophenylmethyl)-2-C-methyl-β-D-ribofuranosyl]-1H-pyrazolo[3,4-d]pyrimidine

To the compound from Step C of Example 62 (1.00 g, 2.02 mmol) indichloromethane (20 mL) was bubbled HBr gas for 5 min until it wassaturated. The resulting solution was stirred at room temperature for 10min, evaporated in vacuo and coevaporated with anhydrous toluene (10mL). 4-Amino-1H-pyrazolo[3,4-d]pyrimidine (Aldrich, 0.43 g, 3.18 mmol)and NaH (60%, 150 mg, 3.8 mmol) were stirred in 1-methyl-2-pyrrolidinone(10 mL) for 30 min. The resulting solution was poured into the abovebromo sugar residue and the mixture was stirred overnight. The mixturewas diluted with toluene (50 mL), washed with brine (10%, 3×50 mL) andconcentrated under reduced pressure. The residue was chromatographed onsilica gel (EtOAc as eluent) to afford a solid (400 mg).

Step B:4-Amino-1-(2-C-methyl-β-D-ribofuranosyl)-1H-pyrazolo[3,4-d]pyrimidine

To a solution of the compound from Step A (0.20 g, 0.33 mmol) indichloromethane (10 mL) at −78° C. was added boron trichloride (1M indichloromethane) (3 mL, 3 mmol) dropwise. The mixture was stirred at−78° C. for 0.5 h, then at −45° C. to −30° C. for 2 h. The reaction wasquenched by addition of sodium acetate (1.0 g) and methanol (10 mL). Thesolution was evaporated and the residue was purified by flashchromatography over silica gel using CH₂Cl₂ and CH₂Cl₂/MeOH (95:5-90:10)gradient as the eluent to furnish the desired compound (60 mg) as asolid, which was recrystallized from methanol and acetonitrile to givethe title compound as an off-white solid (40 mg).

¹H NMR (DMSO-d₆): δ 0.75 (s, 3H), 3.59 (m, 1H), 3.69 (m, 1H), 3.91 (m,1H), 4.12 (m, 1H), 4.69 (t, 1H, J 5.1 Hz), 5.15 (m, 2H), 6.13 (s, 1H),7.68 (s, br, 1H), 7.96 (s, br, 1H), 8.18 (s, 1H), 8.21 (s, 1H).

¹³C NMR (DMSO-d₆): 19.32, 62.78, 74.11, 78.60, 83.65, 90.72, 99.79,133.50, 153.89, 156.21, 158.05.

LC-MS: Found: 282.1 (M+H⁺); calculated for C₁₁H₁₅N₅O₄+H⁺. 282.1.

BIOLOGICAL ASSAYS

The assays employed to measure the inhibition of HCV NS5B polymerase andHCV replication are described below.

The effectiveness of the compounds of the present invention asinhibitors of HCV NS5B RNA-dependent RNA polymerase (RdRp) was measuredin the following assay.

A. Assay for Inhibition of HCV NS5B Polymerase:

This assay was used to measure the ability of the nucleoside derivativesof the present invention to inhibit the enzymatic activity of theRNA-dependent RNA polymerase (NS5B) of the hepatitis C virus (HCV) on aheteromeric RNA template.

Procedure:

Assay Buffer Conditions: (50 μL -total/reaction)

-   -   20 mM Tris, pH 7.5    -   50 μM EDTA    -   5 mM DTT    -   2 mM MgCl₂    -   80 mM KCl    -   0.4 U/μL RNAsin (Promega, stock is 40 units/μL)    -   0.75 μg t500 (a 500-nt RNA made using T7 runoff transcription        with a sequence from the NS2/3 region of the hepatitis C genome)    -   1.6 μg purified hepatitis C NS5B (form with 21 amino acids        C-terminally truncated)    -   1 μM A,C,U,GTP (Nucleoside triphosphate mix)    -   [alpha-³²P]-GTP or [alpha-³³P]-GTP

The compounds were tested at various concentrations up to 100 μM finalconcentration.

An appropriate volume of reaction buffer was made including enzyme andtemplate t500. Nucleoside derivatives of the present invention werepipetted into the wells of a 96-well plate. A mixture of nucleosidetriphosphates (NTP's), including the radiolabeled GTP, was made andpipetted into the wells of a 96-well plate. The reaction was initiatedby addition of the enzyme-template reaction solution and allowed toproceed at room temperature for 1-2 h.

The reaction was quenched by addition of 20 μL 0.5M EDTA, pH 8.0. Blankreactions in which the quench solution was added to the NTPs prior tothe addition of the reaction buffer were included.

50 μL of the quenched reaction were spotted onto DE81 filter disks(Whatman) and allowed to dry for 30 min. The filters were washed with0.3 M ammonium formate, pH 8 (150 mL/wash until the cpm in 1 mL wash isless than 100, usually 6 washes). The filters were counted in 5-mLscintillation fluid in a scintillation counter.

The percentage of inhibition was calculated according to the followingequation: % Inhibition=[1−(cpm in test reaction−cpm in blank)/(cpm incontrol reaction−cpm in blank)]×100.

Representative compounds tested in the HCV NS5B polymerase assayexhibited IC₅₀'s less than 100 micromolar.

B. Assay for Inhibition of HCV RNA Replication:

The compounds of the present invention were also evaluated for theirability to affect the replication of Hepatitis C Virus RNA in culturedhepatoma (HuH-7) cells containing a subgenomic HCV Replicon. The detailsof the assay are described below. This Replicon assay is a modificationof that described in V. Lohmann, F. Korner, J-O. Koch, U. Herian, L.Theilmann, and R. Bartenschlager, “Replication of a Sub-genomicHepatitis C Virus RNAs in a Hepatoma Cell Line,” Science 285:110 (1999).

Protocol:

The assay was an in situ Ribonuclease protection, ScintillationProximity based-plate assay (SPA). 10,000-40,000 cells were plated in100-200 μL of media containing 0.8 mg/mL G418 in 96-well cytostar plates(Amersham). Compounds were added to cells at various concentrations upto 100 μM in 1% DMSO at time 0 to 18 h and then cultured for 24-96 h.Cells were fixed (20 min, 10% formalin), permeabilized (20 min, 0.25%Triton X-100/PBS) and hybridized (overnight, 50° C.) with asingle-stranded ³³P RNA probe complementary to the (+) strand NS5B (orother genes) contained in the RNA viral genome. Cells were washed,treated with RNAse, washed, heated to 65° C. and counted in a Top-Count.Inhibition of replication was read as a decrease in counts per minute(cpm).

Human HuH-7 hepatoma cells, which were selected to contain a subgenomicreplicon, carry a cytoplasmic RNA consisting of an HCV 5′ non-translatedregion (NTR), a neomycin selectable marker, an EMCV IRES (internalribosome entry site), and HCV non-structural proteins NS3 through NS5B,followed by the 3′ NTR.

Representative compounds tested in the replication assay exhibitedEC₅₀'s less than 100 micromolar.

The nucleoside derivatives of the present invention were also evaluatedfor cellular toxicity and anti-viral specificity in the counterscreensdescribed below.

C. Counterscreens:

The ability of the nucleoside derivatives of the present invention toinhibit human DNA polymerases was measured in the following assays.

a. Inhibition of Human DNA Polymerases Alpha and Beta:

Reaction Conditions:

-   50 μL reaction volume    Reaction Buffer Components:-   20 mM Tris-HCl, pH 7.5-   200 μg/mL bovine serum albumin-   100 mM KCl-   2 mM β-mercaptoethanol-   10 mM MgCl₂-   1.6 μM dA, dG, dC, dTTP-   α-³³P-dATP    Enzyme and Template:-   0.05 mg/mL gapped fish sperm DNA template-   0.01 U/μL DNA polymerase αor β    Preparation of Gapped Fish Sperm DNA Template:-   Add 5 μL 1M MgCl₂ to 500 μL activated fish sperm DNA (USB 70076);-   Warm to 37° C. and add 30 μL of 65 U/μL of exonuclease III (GibcoBRL    18013-011);-   Incubate 5 min at 37° C.;-   Terminate reaction by heating to 65° C. for 10 min;-   Load 50-100 μL aliquots onto Bio-spin 6 chromatography columns    (Bio-Rad 732-6002) equilibrated with 20 mM Tris-HCl, pH 7.5;-   Elute by centrifugation at 1,000×g for 4 min;-   Pool eluate and measure absorbance at 260 nm to determine    concentration.

The DNA template was diluted into an appropriate volume of 20 mMTris-HCl, pH 7.5 and the enzyme was diluted into an appropriate volumeof 20 mM Tris-HCl, containing 2 mM 1B-mercaptoethanol, and 100 mM KCl.Template and enzyme were pipetted into microcentrifuge tubes or a 96well plate. Blank reactions excluding enzyme and control reactionsexcluding test compound were also prepared using enzyme dilution bufferand test compound solvent, respectively. The reaction was initiated withreaction buffer with components as listed above. The reaction wasincubated for 1 hour at 37° C. The reaction was quenched by the additionof 20 μL 0.5M EDTA. 50 μL of the quenched reaction was spotted ontoWhatman DE81 filter disks and air dried. The filter disks wererepeatedly washed with 150 mL 0.3M ammonium formate, pH 8 until 1 mL ofwash is <100 cpm. The disks were washed twice with 150 mL absoluteethanol and once with 150 mL anhydrous ether, dried and counted in 5 mLscintillation fluid.

The percentage of inhibition was calculated according to the followingequation: % inhibition=[1−(cpm in test reaction−cpm in blank)/(cpm incontrol reaction−cpm in blank)]×100.b. Inhibition of Human DNA Polymerase Gamma:

The potential for inhibition of human DNA polymerase gamma was measuredin reactions that included 0.5 μg/μL enzyme; 10 μM dATP, dGTP, dCTP, andTTP; 2 μCi/reaction [α-³³P]-dATP, and 0.4 μg/μL activated fish sperm DNA(purchased from US Biochemical) in a buffer containing 20 mM Tris pH8, 2mM β-mercaptoethanol, 50 mM KCl, 10 mM MgCl2, and 0.1 μg/μL BSA.Reactions were allowed to proceed for 1 h at 37° C. and were quenched byaddition of 0.5 M EDTA to a final concentration of 142 mM. Productformation was quantified by anion exchange filter binding andscintillation counting. Compounds were tested at up to 50 μM.

The percentage of inhibition was calculated according to the followingequation: % inhibition=[1−(cpm in test reaction−cpm in blank)/(cpm incontrol reaction−cpm in blank)]×100.

The ability of the nucleoside derivatives of the present invention toinhibit HIV infectivity and HIV spread was measured in the followingassays.

c. HIV Infectivity Assay

Assays were performed with a variant of HeLa Magi cells expressing bothCXCR4 and CCR5 selected for low background β-galactosidase (β-gal)expression. Cells were infected for 48 h, and β-gal production from theintegrated HIV-1 LTR promoter was quantified with a chemiluminescentsubstrate (Galactolight Plus, Tropix, Bedford, Mass.). Inhibitors weretitrated (in duplicate) in twofold serial dilutions starting at 100 μM;percent inhibition at each concentration was calculated in relation tothe control infection.

d. Inhibition of HIV Spread

The ability of the compounds of the present invention to inhibit thespread of the human immunedeficiency virus (HIV) was measured by themethod described in U.S. Pat. No. 5,413,999 (May 9, 1995), and J. P.Vacca, et al., Proc. Natl. Acad. Sci., 91: 4096-4100 (1994), which areincorporated by reference herein in their entirety.

The nucleoside derivatives of the present invention were also screenedfor cytotoxicity against cultured hepatoma (HuH-7) cells containing asubgenomic HCV Replicon in an MTS cell-based assay as described in theassay below. The HuH-7 cell line is described in H. Nakabayashi, et al.,Cancer Res., 42: 3858 (1982).

e. Cytotoxicity Assay:

Cell cultures were prepared in appropriate media at concentrations ofapproximately 1.5×10⁵ cells/mL for suspension cultures in 3 dayincubations and 5.0×10⁴ cells/mL for adherent cultures in 3 dayincubations. 99 μL of cell culture was transferred to wells of a 96-welltissue culture treated plate, and 1 μL of 100-times final concentrationof the test compound in DMSO was added. The plates were incubated at 37°C. and 5% CO₂ for a specified period of time. After the incubationperiod, 20 μL of CellTiter 96 Aqueous One Solution Cell ProliferationAssay reagent (MTS) (Promega) was added to each well and the plates wereincubated at 37° C. and 5% CO₂ for an additional period of time up to 3h. The plates were agitated to mix well and absorbance at 490 nm wasread using a plate reader. A standard curve of suspension culture cellswas prepared with known cell numbers just prior to the addition of MTSreagent. Metabolically active cells reduce MTS to formazan. Formazanabsorbs at 490 nm. The absorbance at 490 nm in the presence of compoundwas compared to absorbance in cells without any compound added.Reference: Cory, A. H. et al., “Use of an aqueous solubletetrazolium/formazan assay for cell growth assays in culture,” CancerCommun. 3: 207 (1991).

The following assays were employed to measure the activity of thecompounds of the present invention against other RNA-dependent RNAviruses:

a. Determination of In Vitro Antiviral Activity of Compounds AgainstRhinovirus (Cytopathic Effect Inhibition Assay):

Assay conditions are described in the article by Sidwell and Huffman,“Use of disposable microtissue culture plates for antiviral andinterferon induction studies,” Appl. Microbiol. 22: 797-801 (1971).

Viruses:

-   Rhinovirus type 2 (RV-2), strain HGP, was used with KB cells and    media (0.1% NaHCO₃, no antibiotics) as stated in the Sidwell and    Huffman reference. The virus, obtained from the ATCC, was from a    throat swab of an adult male with a mild acute febrile upper    respiratory illness.-   Rhinovirus type 9 (RV-9), strain 211, and rhinovirus type 14    (RV-14), strain Tow, were also obtained from the American Type    Culture Collection (ATCC) in Rockville, Md. RV-9 was from human    throat washings and RV-14 was from a throat swab of a young adult    with upper respiratory illness. Both of these viruses were used with    HeLa Ohio-1 cells (Dr. Fred Hayden, Univ. of VA) which were human    cervical epitheloid carcinoma cells. MEM (Eagle's minimum essential    medium) with 5% Fetal Bovine serum (FBS) and 0.1% NaHCO₃ was used as    the growth medium.-   Antiviral test medium for all three virus types was MEM with 5% FBS,    0.1% NaHCO3, 50 μg gentamicin/mL, and 10 mM MgCl₂.-   2000 μg/mL was the highest concentration used to assay the compounds    of the present invention. Virus was added to the assay plate    approximately 5 min after the test compound. Proper controls were    also run. Assay plates were incubated with humidified air and 5% Co₂    at 37° C. Cytotoxicity was monitored in the control cells    microscopically for morphologic changes. Regression analysis of the    virus CPE data and the toxicity control data gave the ED50 (50%    effective dose) and CC50 (50% cytotoxic concentration). The    selectivity index (SI) was calculated by the formula: SI=CC50÷ED50.    b. Determination of In Vitro Antiviral Activity of Compounds Against    Dengue, Banzi, and Yellow Fever (CPE Inhibition Assay)    Assay details are provided in the Sidwell and Huffman reference    above.    Viruses:

Dengue virus type 2, New Guinea strain, was obtained from the Center forDisease Control. Two lines of African green monkey kidney cells wereused to culture the virus (Vero) and to perform antiviral testing(MA-104). Both Yellow fever virus, 17D strain, prepared from infectedmouse brain, and Banzi virus, H336 strain, isolated from the serum of afebrile boy in South Africa, were obtained from ATCC. Vero cells wereused with both of these viruses and for assay.

Cells and Media:

-   MA-104 cells (BioWhittaker, Inc., Walkersville, Md.) and Vero cells    (ATCC) were used in Medium 199 with 5% FBS and 0.1% NaHCO₃ and    without antibiotics.-   Assay medium for dengue, yellow fever, and Banzi viruses was MEM, 2%    FBS, 0.18% NaHCO3 and 50 μg gentamicin/mL.-   Antiviral testing of the compounds of the present invention was    performed according to the Sidwell and Huffman reference and similar    to the above rhinovirus antiviral testing. Adequate cytopathic    effect (CPE) readings were achieved after 5-6 days for each of these    viruses.    c. Determination of In Vitro Antiviral Activity of Compounds Against    West Nile Virus (CPE Inhibition Assay)-   Assay details are provided in the Sidwell and Huffman reference    cited above. West Nile virus, New York isolate derived from crow    brain, was obtained from the Center for Disease Control. Vero cells    were grown and used as described above. Test medium was MEM, 1% PBS,    0.1% NaHCO3 and 50 μg gentamicin/mL.-   Antiviral testing of the compounds of the present invention was    performed following the methods of Sidwell and Huffman which are    similar to those used to assay for rhinovirus activity. Adequate    cytopathic effect (CPE) readings were achieved after 5-6 days.    d. Determination of In Vitro Antiviral Activity of Compounds Against    Rhino, Yellow Fever, Dengue, Banzi, and West Nile Viruses (Neutral    Red Uptake Assay)

After performing the CPE inhibition assays above, an additionalcytopathic detection method was used which is described in “MicrotiterAssay for Interferon: Microspectrophotometric Quantitation of CytopathicEffect,” Appl. Environ. Microbiol. 31: 35-38 (1976). A Model EL309microplate reader (Bio-Tek Instruments Inc.) was used to read the assayplate. ED50′s and CD50's were calculated as above.

Example of a Pharmaceutical-Formulation

As a specific embodiment of an oral composition of a compound of thepresent invention, 50 mg of Example 61 or Example 62 is formulated withsufficient finely divided lactose to provide a total amount of 580 to590 mg to fill a size O hard gelatin capsule.

While the invention has been described and illustrated in reference tospecific embodiments thereof, those skilled in the art will appreciatethat various changes, modifications, and substitutions can be madetherein without departing from the spirit and scope of the invention.For example, effective dosages other than the preferred doses as setforth hereinabove may be applicable as a consequence of variations inthe responsiveness of the human being treated for severity of the HCVinfection. Likewise, the pharmacologic response observed may varyaccording to and depending upon the particular active compound selectedor whether there are present pharmaceutical carriers, as well as thetype of formulation and mode of administration employed, and suchexpected variations or differences in the results are contemplated inaccordance with the objects and practices of the present invention. Itis intended therefore that the invention be limited only by the scope ofthe claims which follow and that such claims be interpreted as broadlyas is reasonable.

1. A method of treating hepatitis C virus (HCV) infection comprisingadministering to a mammal in need of such treatment a therapeuticallyeffective amount of a compound of structural formula III, or apharmaceutically acceptable salt or acyl derivatives thereof,

wherein B is

W is O or S; Y is H, C₁-10 alkylcarbonyl, P₃O₉H₄, P₂O₆H₃, or P(O)R⁹R¹⁰;R¹ is CF₃, or C₁₋₄ alkyl and one of R² and R³ is OH or C₁₋₄ alkoxy andthe other of R² and R³ is fluoro; R⁶ is H, OH, SH, NH₂, C₁₋₄ alkylamino,di(C₁₋₄ alkyl)amino, C₃₋₆ cycloalkylamino, halogen, C₁₋₄ alkyl, C₁₋₄alkoxy, or CF₃; R⁵ is H, C₁₋₆ alkyl, C₂₋₆ alkenyl, C₂₋₆ alkynyl, C₁₋₄alkylamino, CF₃, or halogen; and R⁹ and R¹⁰ are each independentlyhydroxy, OCH₂CH₂SC(═O)t-butyl, or OCH₂O(C═O)iPr.
 2. The method of claim1 wherein a compound of structural formula III, or a pharmaceuticallyacceptable salt or acyl derivatives thereof is in combination with atherapeutic amount of another agent active against HCV infectionselected from the group consisting of ribavirin; levovirin; thymosinapha-1; an inhibitor of NS3 serine protease; an inhibitor of inosinemonophosphate dehydrogenase; and interferon-α or pegylated interferon-α.